Chuck Smith emphasizes that God knows our hearts and desires us to give our hearts fully to Him. He explains that mere knowledge or belief is insufficient for salvation; true belief must come from the heart, which involves our will and actions. Smith illustrates this with examples from David and Abraham, showing that God values our intentions and willingness over mere actions. Ultimately, he urges listeners to reflect on their hearts and ensure they have truly surrendered to God, as He is aware of our innermost thoughts and feelings.