Galatians 6:8. “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.”
Following up in the simple principle of sowing and reaping, Paul teaches that those who never come to Christ, who continue to please their flesh and never come to repentance, will reap the destruction of the flesh. They will not spend eternity in heaven with God.
But those who, having come to Christ for salvation and begin to walk in the Spirit, desiring to please God, have been truly born again and will reap eternal life. It’s simple, really.
Ecclesiastes 12: 13-14.
13 Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.
14 For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil.