You may think that you have a guaranteed spot in heaven. Perhaps it is because of the good deeds you have done or the fact that you have never missed a Sunday at Church or the fact that you tell everyone you meet that Jesus is your Lord and Savior. The truth is that many people on their day of judgement will arrogantly approach the great white throne of Christ only to be thrust away into the worst place imaginable where they will spend all eternity.
Jesus said, "Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, 'Lord, Lord, did we not prophecy in your name, and cast our demons in your name, and do many mighty works in your name?' And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness.'" (Matthew 7:21-23) According to Jesus, you cannot prophecy your way into heaven. Nor can you earn a spot in his kingdom by casting out demons or by any great work for that matter. "For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast." (Ephesians 2:8-9)
Jesus is the reason we get to go to heaven. He lived the perfect, sinless life that we could not, and he drank the cup of his father's wrath that was meant for us. He is our way into heaven. We were purchased by his blood and those who believe in him have been made new creations in his image.
So how do you know for sure if you indeed are "saved" and will one day inherit the kingdom of God? Paul says that we are to "Examine yourselves, to see whether you are in the faith. Test yourselves." (2 Corinthians 13:5) Jesus said that a tree is known by its fruit, meaning that Christians should live their lives the way Jesus lived. He was humble enough to wash the feet of his disciples. He was obedient to his father, even to the point of death on a rugged cross. He was sinless. We, however, will never be sinless, but we can certainly sin less! Repentance is the act of forsaking sin for a relationship with God through Jesus and it is mandatory.
Paul paints an amazing picture of what a fruit-bearing Christian life should look like in this amazing passage, "But I say, walk by the Spirit, and you will not gratify the desires of the flesh. For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do. But if you are led by the Spirit, you are not under the law. Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God. But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law. And those who belong to Christ Jesus have crucified the flesh with its passions and desires." (Galatians 6:16-24)
Do not forget that salvation is a free gift from God. We did not deserve it. He purchased us with the precious blood of his son, Jesus. Do not be the one who on the day of judgement arrogantly approaches his throne only to be thrust away, but rather be the one who humbly stands before the King of Kings, the one who gave it all. "For the Lord sees not as man sees: man looks on the outward appearance, but the Lord looks on the heart." (1 Samuel 16:7)