How do we know that faith is necessary for salvation?

In his sermon, the preacher emphasizes that faith is not a meritorious work but rather the vehicle through which God's election and grace are realized in the believer's life. Ephesians 2:8-9 clearly states that by grace we are saved through faith, and that not of ourselves, implying that faith itself is a gift from God. Thus, faith is essential because it acknowledges our complete reliance on God's mercy and grace while denying any room for boasting in our own efforts. By establishing this necessity, we understand that our salvation is ultimately determined by God's will and purpose, not our deeds.