'Unstable' in the Bible

a two-souled man is unstable in all his ways.

having eyes full of adultery, and unable to cease from sin, enticing unstable souls, having an heart exercised in covetousnesses, children of a curse,

as also in all the epistles, speaking in them concerning these things, among which things are certain hard to be understood, which the untaught and unstable do wrest, as also the other Writings, unto their own destruction.