You and I change no one. Ultimately, personal change comes from only one source: the gracious act of a powerful God. When people try to change one another, typically the focus is on the behaviour. Yet behaviour is not really the issue. If a person’s words, actions, choices, decisions, reactions, or responses are other than what God would want them to be then the root problem is not behaviour, but the heart.

Paul Tripp, Broken Down House, p.65