How do we know that faith must happen in the heart?

Faith must happen in the heart because it is the heart that truly hears God's message. As 1 Corinthians 2:14 states, 'the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him.' This indicates that without the heart being changed, one cannot comprehend spiritual truths. Thus, genuine faith must originate from a transformed heart, wherein one is enabled by the Holy Spirit to understand and embrace the gospel. Therefore, faith is not just an intellectual assent but a deep, heartfelt belief that connects one to Christ.