Christian faith involves the whole person. The biblical term that best captures this concept is heart. Proverbs 4:23 puts it this way, “Above all else, guard your heart, for it is the wellspring of life.” The term “heart” in the Bible includes the intellect, emotion, and will. Theologian Robert Saucy summarizes, “It is important to grasp the biblical truth that in the heart, the operating center from which all behavior flows, thought, feeling, and will all come together in a unified whole.” Taken in this holistic sense, a person trusts Christ with the heart. In this act, cognitive, volitional, and affective elements converge. Christian faith is neither irrational nor opposed to reason. However, it includes more than just rational content.
According to the New Testament, the Holy Spirit is intimately involved in any person’s coming to faith in Jesus Christ (cf. John 16:8–11). I can’t put it any better than David Clark does, “The Holy Spirit permeates this process. He works to overcome the blinding effects of sin and to lead a person toward openness to the Christian message. The role of the sensitive apologist [or evangelist] is to defend the truth that the Holy Spirit then drives home to a needy heart and mind. As minimal Christian truth initially sinks in and is intellectually acknowledged, the Holy Spirit persuades a person to respond to the Person the truth reveals. When response comes, understanding is deepened. Another step of deeper reliance is possible. And the process of growth continues.”