Who Is An Unbeliever?
Unbelief can cause one to be eternally lost. The Bible says, "And to whom did God swear that they would never enter His rest if not to those who disobeyed? So we see that they were not able to enter, because of their unbelief" (Hebrews 3:18-19). One who does not believe God cannot enter into Godís rest of Heaven, but will be cast into the eternal torments of Hell. When one does not obey the Lordís commands, God counts this as unbelief. Jesus says, "But why do you call Me Lord, Lord, and not do the things which I say?" (Luke 6:46). If one doesnít keep Godís commandments, this shows that one doesnít really believe God. We read in 1 John 2:4, "He who says, ĎI know Himí, and does not keep His commandments is a liar, and the truth is not in him." One who says he knows God, but does not keep His commandments is not only lying to others but also to himself.
We are warned, "Beware, brethern, lest there be in any of you an evil heart of unbelief in departing from the living God" (Hebrews 3:12). A Christian becomes an unbeliever when he departs from God by not faithfully serving Him. God says, "But the cowardly, unbelieving, abominable, murderers, sexually immoral, sorcerers, idolaters, and all liars shall have their part in the lake which burns with fire and brimstone, which is the second death" (Revelation 21:8). One doesnít have to do anything to be lost, except to be an unbeliever. One may claim to be a believer, but if he doesnít faithfully obey God, he is an unbeliever. If one doesnít believe God, he will not obey Him. Jesus is only "the author of eternal salvation to all who obey Him" (Hebrews 5:9).