'Simplicity' in the Bible

Two hundred men went with Absalom out of Jerusalem, who were invited, and went in their simplicity; and they didn't know anything.

"How long, you simple ones, will you love simplicity? How long will mockers delight themselves in mockery, and fools hate knowledge?

But I am afraid that somehow, as the serpent deceived Eve in his craftiness, so your minds might be corrupted from the simplicity that is in Christ.