by Matt Slick
Sincerity does not enable someone to go to Heaven. If sincerity were all that was necessary, then any sincere person who believed most anything could make it to Heaven. That means Mormons who sincerely believe that God came from another planet and has a goddess wife would make it to Heaven. It would also mean that Muslims who sincerely believe that Jesus is not God in flesh and did not die on the cross for our sins would also go to Heaven. It would mean that atheists would go to Heaven if they are sincere people and do good. But this is false.
Appealing to sincerity as a reason to be able to go to Heaven is appealing to pride. This is because pride is a high opinion of one's own self or quality, or merit, or ability, etc. If a person is appealing to his own sincerity as a justification by which he can go to Heaven, then he is appealing to a quality within himself which merits the ability to go to Heaven. It also means that the person is not trusting in what God has done but is trusting in his own heart and goodness. All of this is pride because it is self-centered and is implying a person is good enough to be with God on his own.
Jesus said, "For from within, out of the heart of men, proceed the evil thoughts, fornications, thefts, murders, adulteries, 22 deeds of coveting and wickedness, as well as deceit, sensuality, envy, slander, pride and foolishness. 23 “All these evil things proceed from within and defile the man" (Mark 7:21-23). So, our hearts, the place where sincerity resides, is a place of wickedness. This is not to say that every thought and every intention is pure evil, but it does mean that our hearts are not good enough.
In order to go to Heaven, a person must have faith in the work of Jesus Christ and not his own work. A person must put faith and trust in the sacrifice of Jesus who was made under the law (Galatians 4:4), who had greatly humbled himself by being a man (Philippians 2:5-8), who lived a perfect life (1 Peter 2:22), who bore our sins in His body on the cross (1 Peter 2:24), and died and rose from the dead three days later (1 Corinthians 15:1-4). To be made right with God, to be justified, can only be by faith and not by our works or the condition of our hearts because everything we do is touched by sin. Therefore, salvation and being able to go to Heaven is by faith alone in Christ alone (Romans 3:28, 4:1-5, 5:1, John 3:16, Ephesians 2:8-9).