How do we know God's grace is the cause of our salvation?

According to the genuine gospel, God's grace is the foundation of our salvation. Philippians 2:13 states that it is God who works in us both to will and to do according to His good pleasure. This clear declaration affirms that there is nothing in us that merited God's grace. Instead, it is by His free will and purpose that we are saved. Understanding that we contribute nothing to our salvation underscores the sheer magnitude of God's grace, which is vital for our faith and assurance in Him.