1Samuel 12:21 And turn ye not aside: for then should ye go after vain things, which cannot profit nor deliver; for they are vain.
They chose a king and angered God. Samuel warns them that God will not forsake them even though they have sinned. He especially warns them to not fall into the trap of vain things because of their previous failure.
Satan would like nothing more than to remind us of our past failures as a reason to turn from God and follow worthless, empty things. You messed up. It is too late. You might as well go deeper into sin! All of these are lies from the devil to deceive us.
Though you have failed and are very sorry do not allow Satan to cause you to go into even more sin. Recognize what you did. Turn to the Lord and seek Him. He will not forsake you.
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