'Unstable' in the Bible

"Look, I am making Jerusalem an unstable cup toward all of its surrounding armies when they lay siege against Judah and Jerusalem.

He is a double-minded man, unstable in all he undertakes.

He speaks about this subject in all his letters. Some things in them are hard to understand, which ignorant and unstable people distort, leading to their own destruction, as they do the rest of the Scriptures.