Universalism is a contemptible and utterly vile doctrine. I will go so far as to say that any church which preaches universalism and teaches others to do so is most likely apostate from Christ, and condemned to hell themselves. The Bible is replete with statements that not believing in Christ is a sin that is worthy of eternal comdemnation. It is written,
Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him. (John 3:36)
Jesus said that he was the only way to God, apart from other false religions. This includes Judaism, Islam, Hinduism, Buddhism, atheism, and any other theistic or atheistic religion that does not teach salvation by faith in Christ. The Apostle John, who wrote that "God is love" (1 John 4:16), also was so bold as to say,
Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, he who denies the Father and the Son. No one who denies the Son has the Father. Whoever confesses the Son has the Father also. (1 John 2:22-23)
Again John, who is often called "the Apostle of Love," said that non-Christian religions can never result in salvation,
Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son. (2 John 1:9)
Elsewhere the same Apostle says that the punishment for rejecting Jesus is an eternal one,
And the smoke of their torment goes up forever and ever, and they have no rest, day or night, these worshipers of the beast and its image, and whoever receives the mark of its name. (Revelation 14:11)
The Apostle Paul, who taught extensively on the love and grace of God, said that God will inflict his eternal wrath and pour out his anger on all non-Christians,
This is evidence of the righteous judgment of God, that you may be considered worthy of the kingdom of God, for which you are also suffering-- since indeed God considers it just to repay with affliction those who afflict you, and to grant relief to you who are afflicted as well as to us, when the Lord Jesus is revealed from heaven with his mighty angels in flaming fire, inflicting vengeance on those who do not know God and on those who do not obey the gospel of our Lord Jesus. They will suffer the punishment of eternal destruction, away from the presence of the Lord and from the glory of his might, when he comes on that day to be glorified in his saints, and to be marveled at among all who have believed, because our testimony to you was believed. (2 Thessalonians 1:5-10)
It is clear, therefore, that God will not grant even the slightest degree of mercy to those who chose to reject his Son and practice other religions, but instead will give them what justice demands for all humans: eternal condemnation and destruction. This is not a joke or a scare tactic, but a very real fruit of false religion. Here in Scripture, in the lively oracles of God, we see that God is ready to punish sinners for our disobedience, but offers forgiveness through the blood of his Son Jesus. It does not come by keeping the laws of rabbis, obeying five pillars, performing pujas, or detaching yourself from the world, but by faith in Christ Jesus.
In light of what a serious sin it is to practice other religions, how terrible it is that there are churches in the world which actually teach that non-Christians can be saved. Such a teaching treats the blood of Jesus like dirt and denies the faith. It constitutes anathema, as the Bible says,
As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed. (Galatians 1:9)
Churches which teach that non-Christians can be saved believe that they are being loving towards non-Christians. The Catholic Church, for example, believes that it can make up for centuries of anti-semitism by teaching that Jews are already in a covenant relationship with God and are not in need of the Gospel of Christ. In this way they are insuring the eternal condemnation of many Jews, and are only completing their anti-semitism. Churches which teach universalism make themselves into ministers of condemnation. They hand the world over to Satan and drive people into hell. They shut the kingdom of heaven in men's faces and refuse to enter themselves. I urge no one here to believe the lie that you can reject Jesus and not go to hell for it. Many will ask me what happens to people who have never heard about Jesus. If you have read my post to this point then for you the question is moot. If you reject Christ you will go to hell, and there will be no escape.