How do we know that salvation is a heart work?

Salvation is described as a heart work because true faith and belief are rooted in a transformed heart. Acts 8:21 reveals how God assesses the heart, emphasizing that true faith cannot be based merely on outward appearances or actions. In the case of Simon, he seemingly believed but did not possess a heart that was genuinely seeking Christ. The text cautions us that simply participating in religious activities does not equate to salvation. A true work of salvation occurs when the Holy Spirit transforms the heart, leading one to genuinely trust in and seek Christ above all else.