Question:
What are the consequences of doing sin on earth?

Answer:
“Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap. For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting” (Galatians 6:7,8).

Hebrews 12:6-11: The Lord “chastens” or trains whom He loves. If we’re not living our lives as we should, we put ourselves into a position for God to make us sick and even die (1 Corinthians 11:27- 34). It is very important to, in sorrow, confess and be done with our sin as soon as possible, and accept His forgiveness (1 John 1:9). God always has our best in mind no matter what happens (Psalm 32:3-5).
But if we should marry an unbeliever, we are disobeying the Lord and will only reap much sorrow and suffering in that marriage (2 Corinthians 6:14). First Corinthians 7:12-17 and first Peter 3:1 show how a spouse is to behave if married to an unbeliever. The saved one should not initiate a divorce.
Psalm 19:12-14 is what will be true of us if the Word is valued, “sweeter also than honey and the honeycomb” (verse 10), and hidden in our hearts. We will not want to displease the Lord in any way.
First Corinthians 6:18 shows that fornication is a sin worse than others against the physical body of those who do it. But eternally speaking, all sins are equal for those who are saved, but the unsaved get different degrees of punishment.