Faith is central to Christianity. The New Testament repeatedly calls people to believe in the Lord Jesus Christ. Until the Holy Spirit changes us, we have hearts of stone. An unregenerate heart is without affection for Christ; it lacks compassion for other people. We are like that by nature. We are selfish and self centered. The Holy Spirit changes the intent of our hearts so that we see the sweetness of People and Christ and we embrace Him.None of us loves Christ perfectly, but we cannot love Him at all unless the Holy Spirit changes the heart of stone and makes it a heart of flesh.
Faith is effectual only if one personally trusts in Christ alone for salvation.