The above painting is michelangelo buonarroti’s, last judgement. what is/was the source of inspiration for this famous painting? what does the painting depict?

David is depicted before his battle with The giant Goliath.
Instead of being shown victorious over a foe much larger than Himself, David looks tense and ready for combat.
 so its a christian type thing it portrays even though he knew he could win he was still scared and worried

Idon't inderstandhthe question