Ephesians 6:10-13

Finally, be strong in the Lord and in the strength of his might. Put on the whole armor of God, that you may be able to stand against the schemes of the devil. For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm.

1 John 3:4-10

Everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness. You know that he appeared in order to take away sins, and in him there is no sin. No one who abides in him keeps on sinning; no one who keeps on sinning has either seen him or known him. Little children, let no one deceive you. Whoever practices righteousness is righteous, as he is righteous. Whoever makes a practice of sinning is of the devil, for the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the works of the devil. No one born of God makes a practice of sinning, for God's seed abides in him; and he cannot keep on sinning, because he has been born of God. By this it is evident who are the children of God, and who are the children of the devil: whoever does not practice righteousness is not of God, nor is the one who does not love his brother.

Question: Why must believers keep killing sin, and how do we know the fight ends in life?

Answer: Because we owe the flesh nothing; the Holy Spirit lives in us to put sin to death—and His leading proves we are God’s adopted children, heirs of eternal life.

Romans 8:14
“For all who are led by the Spirit of God are sons of God.”