There are several arguments against believing the doctrine of universal reconciliation.  For the sake of brevity, I will address only a few of them.
 

Argument 1

If this doctrine is true, why don't most Christians believe it?

Just because the majority either believes or disbelieves in something, that doesn't necessarily make it right.  Take Israel for example.  It is clear to us that all throughout the Old Testament, God's intention was always to include the Gentiles in His "greater" purpose. And yet, Israel as a whole rejected the prophets and their message.  They could not see the truth that we now see.  They limited God's plan to their own dispensation.

The Roman Church embraced such falsehoods as Transubstantiation and rejected truths such as the doctrine of Justification by Faith.  It wasn't until Martin Luther that God broke through the traditions of men and the truth became clear to the Church.

The problem with the Church today is that we see ourselves better and far above Israel, when in reality, we are just like her.

Listen to the words of Andrew Jukes:

But suppose it were otherwise,--suppose it could be shown that the Church, instead of asserting "the forgiveness of sins," had taught the reverse, and had judged the doctrine of the "restitution of all things" as false--what does this prove, if, though yet beyond the Church's light, the doctrine is really taught in the Holy Scriptures?  Many things have been hid in Scripture for ages.  St. Paul speaks of "the revelation of the mystery, which had been hid from ages and generations;" some part of which at least, though hidden, had been "spoken by the mouth of all God's holy prophets since the world began."  There are many such treasures hidden in Scripture, open secrets like those in nature which are daily opening to us.

But when have God's people as a body ever seen or received any truth beyond their own dispensation?  Take as an instance Israel of old, whose ways, "ensamples of us," prefigure the Church of this age.  Did they ever receive the call of the Gentiles, or see God's purpose outside their own election?  A few all through that age spoke of blessings to the world, and were without exception judged for such a testimony:--"Which of the prophets have not your fathers slain?"  Was God's purpose to the Gentiles therefore a false doctrine: or, because His people did not receive it, was it not to be found in their own Scriptures?

The doctrine of the "restitution of all things" is to the Church what "the call of the Gentiles" was to Israel.  And if the Church, like Israel, can see no truth beyond its own and has judged those who have been witnesses to a purpose of love far wider than that of this age,--which is not to convert the world, as some suppose, but only "to take out of the nations a people for God's name,"--is God's purpose, though declared in Scripture, to be damned as false doctrine simply because the Church is blind to it?  Is Israel's path to teach us nothing?  Are men's traditions as to God's purpose to be preferred to His own unerring Word?

It is indeed a solemn thing to differ with the Church, or like Paul to find oneself in a "way which they call heresy," simply by "believing," not some but, "all the things which are written in the law and the prophets."  But the path is not a new one for the sons of God.  All the prophets perished in Jerusalem.  And, above all, the Lord of prophets was judged as a Deceiver, by those whom God had called to be His witnesses.  The Church's judgment, therefore, cannot decide a point like this, if that judgment be in opposition to the Word of God.

But is it possible that Christians should have been allowed to err on so important a point as the doctrine of future judgment?  Would our Lord Himself have used, or permitted others to use, words which, if final restitution be true, might be understood as teaching the very opposite.  Transubstantiation is a mistake built on Christ's very words; and the doctrine of endless torments is but another like misunderstanding; which not only directly contradicts many other Scriptures, but practically denies and falsifies the glorious revelation of Himself, which God has given us in the gospel, and in the face of Jesus Christ.  This shows us the state of the Church.  And though thousands of God's children have held, not this only, but many other errors, the fact, instead of approving their errors, only proves the grace of Him, who spite such errors can yet bless and make His children a blessing

Argument 2

Why did Jesus have to die if all men are going to be saved anyway?

That’s like asking, "What’s the point of having a hospital that has discovered the cure for all diseases?"  Just because Calvary will prove itself to be 100% successful does not render Christ’s sacrifice unnecessary.  If a rescue team saved all the passengers on a sinking ship, would that prove their mission to be futile?  The unscriptural dogma that only some will be saved undermines the atonement.  It renders our Lord’s work as mostly a failure. There is no other name by which men can be saved (Acts 4:12)!  This is God’s way.  God could have chosen any means He wanted to bring salvation to men.  The means God has chosen to bring it about is the shedding of innocent blood.  Man cannot save himself.  He is estranged from God because of sin.  So God had to intervene and send His only Son to die for the sins of the world.  This was God’s plan before the foundation of the world.  So even if God were going to save only one man, Jesus would still have had to die.  So it really doesn’t matter if one man is saved or all of mankind, Jesus Christ fulfilled the purpose of God by dying for the sins of the world.  This is the only way to be saved.  This is the way God has chosen.  Let us now be silent on the issue.

Argument 3

If men know they will be saved one day, this will lead to a license to sin.  They will have no reason to repent in this life.

This was the same argument that men gave the Apostle Paul as he preached the “gospel of grace.”  They argued salvation by grace apart from the law would lead men to continue in sin.  It was said that the law was needed to keep men in line.  This is the exact reason why Paul wrote in Rom 6:1, “What shall we say then?  Shall we continue in sin that grace may abound…?”

The reason men should repent in this life is the fact that they are in a condemned state without Christ.  God’s judgmental fire is coming.  Yes, there will be rewards (and lack of them) for what we’ve done here on this earth.  There are many reasons why men should repent now.  But the bottom line is this: men should repent now because God sent His Son to die for their sins.  They can have life now!  They don’t have to continue being dead in their trespasses.  This is the Good News!  Men no longer have to be estranged from God.  They can have His love, joy, and peace today!

Argument 4

Why should we preach if God we save all one day?

I hate to keep giving simple answers but we proclaim His truth simply because God commands us to!  We are His priests and one of the functions of a priest is to go to men on behalf of God.  We are to perform our priestly duties by going to men with the good news of Jesus Christ.  When they get saved is not our business.  Some will sow: some will reap.  But it is God who will give the increase in His own time.

God has called us to a glorious calling: to proclaim His liberty to the captives!  He has chosen the Church (the elect, firstborn sons, etc.) to be the vehicle in which to tell the whole world about the love of God in Christ.

If universal reconciliation is true (and it is), how terrible for me if I were to sit at home with the attitude that "I'm not gonna do anything because every person will be saved eventually anyway."  When I stand before my Lord face to face, not only will I be ashamed of my attitude, but I will be so disappointed that I missed out on opportunity after opportunity to be a partaker in the high calling of God.  What joy it is to see a soul saved, to see one receive the truth, to see one set free from sin, to see a little one find his or her Father; And what joy for me to know that God used litle ol' me to participate in His glorious plan of restoration!

This is our calling! This is our joy! This is our privledge!

Argument 5

You’re saying that God will give men a second chance after they die.

Isn’t our God the God of second chances?  How many chances did He give you and me?  How many times did we reject Him before we responded to His call of grace?  Heb 9:27 says, “It is appointed for men once to die, then the judgment.”  Men will die physically and then there is a judgment.  But even Christians are not exempt.  1 Cor 3 speaks of a judgment of believers.  We will all die physically and stand before God in judgment.  But nowhere in this verse does it say that salvation cannot come after judgment.  In fact, the whole purpose of judgment is rehabilitative in nature, not penal.  If you doubt this, read Matt 25:46.  The word used for punishment is the Greek word “kolasis” which means “to prune.”  It is remedial in nature.  The way the verse should read is, “…and these shall go away into age-abiding correction.”  And as we’ve already seen, nowhere in the Scriptures can you find a word meaning “eternal” linked with punishment.

Argument 6

But doesn’t the Bible say that the ungodly will not inherit the Kingdom of Christ and of God (Eph 5:5)?

This is one of the tough passages that seem to contradict the doctrine of universal salvation.  However, I believe 1 Cor 15:24-28 answers this dilemma.  Most Christians do not understand that one day the Kingdom of Christ will come to an end.  Paul talks of a day when the reign of Christ will end, when Christ will step off His throne and subject Himself to the Father so that God may be all in all.  This “Kingdom” age will be the time when God will continue to work out His purpose in the earth.  I believe it is during this reign of Christ where the ungodly men will be receiving their judgment in the Lake of Fire.  Once this judgment is complete, death will finally be destroyed, men will be restored back to their creator, and God will be all in all.

It is absolutely true that no ungodly person shall inherit the Kingdom of Christ and of God.  The truth is that the second death will destroy every motive, every imagination, and every deed that is in opposition to God.  When this final death accomplishes its purpose, every soul will be purged and be made ready to receive the Lord Jesus Christ.   Every man, woman, and child must go through this "death to the flesh."  The Christian goes through this death now.  The wicked go through a more harsh death in the ages to come.  However, the result is the same.  All wickedness will be destroyed!  All of us must be purged and be made ready to inherit the Kingdom of God.

Argument 7

What about Adolf Hitler?  Will God save Him too?

I’ve included this argument because it always comes up.  This argument really gets to the heart of the problem.  We think that “we” are so much better than others.  We would never commit murder or rape.  We would never beat our wives or lie or steal.  So we look at someone like Adolph Hitler and put him in a worse category than ourselves.  It seems to me Rom 3:23 indicts us all—“For all have sinned and come short of the glory of God.”

This argument really comes down to the “spirit” of Jonah.  Why did Jonah get angry when all of Nineveh repented?  Simply this: he was prideful.  He thought that he was better than those wicked Ninevites.  And so he got angry when God spared their lives.  Isn’t this the same thing we see today?  Oh sure, we talk about how much we love those “terrible sinners.”  But when they get saved, we feel betrayed by God.  That “terrible sinner” who was far worse than we ever were is now going to share heaven with us.  It is the same spirit that Jesus was talking about when he told the parable of the laborers who each got hired at different times of the day.  But in the end, they all got paid the same wage.  Those who got hired early in the morning got angry with the master because they felt they deserved more.

This is much of the same spirit we see in the Church today.  The doctrine of eternal torment feeds the pride of man.  It makes us cold and hard.  We try to mask it behind our “words of love,” but the true spirit (the flesh) of Jonah is there.  It is not until we see ourselves as Paul did, wretched and the chief of all sinners, that the doctrine of universal reconciliation can become a glorious truth in our lives.  And until the “power of sin” is broken in our own lives, we will continue to embrace those things that please the flesh—things that only bring death and not life.

In Conclusion

We really think too highly of ourselves.  We’ve got God all figured out.  We have our nice, neat, and tidy theology all wrapped up and our impressive doctorate degrees hanging on our walls.  But the truths of God are far greater than any of our earthly wisdom.  We say we are taught of the Holy Spirit, but are we?  The early Church needed no Bible colleges.  They needed no degrees.  They needed no special positions or offices.  All they had was the Holy Spirit to teach them.  I’m afraid we’ve been taught too much by the traditions of men and have relied very little on the Holy Spirit.  May God grant us a spirit of humility to see who we are in the light of His unsearchable riches.