How do we know our profession of faith is true?

In the sermon, it is outlined that the presence of the Holy Spirit is the sign of God affirming one's profession of faith. Romans 8:9 states that if anyone does not have the Spirit of Christ, he does not belong to Him. The Holy Spirit not only assures us of our belonging to God but also works in us to reveal Christ and guide us in truth. This internal change signifies the validity of our faith, transforming us from hypocrites to true believers, empowered by grace. It is through the Spirit that we come to faith, see Christ clearly, and acknowledge our dependence on Him for salvation.