'Continue' in the Bible

What shall we say then? Shall we continue in sin, that grace may abound?

Behold then the goodness and severity of God: toward them that fell, severity; but toward thee, God's goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.

And they also, if they continue not in their unbelief, shall be grafted in: for God is able to graft them in again.