Theoretical vs practical disbelief

A brilliant quote from Tim Chester's blog:

Problems for Christians do not often arise because of disbelief in a confessional or theoretical sense (though this may be case). More often they arise from functional or practical disbelief. Asked if I belief in justification by faith, I may reply that I do (confessional faith), but still feel the need to prove myself (functional disbelief). I may affirm that God is sovereign (confessional faith), but still get anxious when I cannot control my life (functional disbelief). Indeed, sanctification can be viewed as the progressive narrowing of the gap between confessional faith and functional faith.