Why did David pretend to be insane?
David was not safe in Israel since Saul sought to kill him. He thought he would be safer with the enemies, the Philistines. The Bible does not say why David thought he would be safer with the Philistines. Perhaps he thought they would not recognize him as the one who killed Goliath, and that they would welcome him as a wayfaring stranger. The Bible does say that when David arrived in the Philistine town, people recognized him right away. After all, in addition to killing Goliath, David had a reputation for exceptional military prowess.
David became afraid when the Philistines recognized him. Would they imprison him? Kill him? So David pretended to be insane: “pounding his head on the city gate and foaming at the mouth, spit dripping from his beard.” (The Message, I Samuel 21:13) The Philistines wanted nothing to do with him. Achish the king said, “Can’t you see he’s crazy? Why did you let him in here? Don’t you think I have enough crazy people to put up with as it is without adding another? Get him out of here!” (The Message, I Samuel 21:15) And so, David managed to escape.
2. NebuchadnezzarNebuchadnezzar twice admits the power of the God of the Hebrews: first, after God saves three of Daniel’s companions from a fiery furnace (Daniel 3); and secondly, after Nebuchadnezzar himself suffers a humiliating period of madness, as Daniel predicted (Daniel 4). Nebuchadnezzar was humbled by God for boasting about his achievements, lost his sanity and lived like an animal for seven years, according to Daniel, chapter 4. When his sanity was later restored he praised and honoured God.
https://www.openbible.info/topics/crazy
https://www.openbible.info/topics/insanity
Psychiatry?
https://biblereasons.com/mental-illness/
If we are “out of our mind,” as some say, it is for God; if we are in our right mind, it is for you.