Cain was fearful of death ..became naked. Fear is from sin and guilt. Cain had self-preserving fear. self-righteous.
Being naked is being incompatible with infinity. Righteous Everlasting Life.
“And the LORD said to him, "Therefore, whoever kills Cain, vengeance shall be taken on him sevenfold." And the LORD set a mark on Cain, lest anyone finding him should kill him” (Genesis 4:15)
i think GOD was trying to help Cain’s fears by telling him there was The Way back to safety ..Life. I think we are Cain. We get the Mark of GOD for Everlasting Life.