"This is precisely why the cry, "Abba! Father," is so significant. It expresses, at a point of intense need, an instinct that is absent from the unbeliever's consciousness. At best such a person may (and often does) cry out, "O God!" but not instinctively, "O Father!" That cry is the fruit of the ministry of the Spirit; it is his co-testimony with our spirit; even in the hour of darkness the believer possesses an instinct, a testimony: he or she knows him- or herself to be a child of God!"