How do we know that doing God's will is essential for salvation?

In Matthew 7:21, Jesus underscores that not everyone who claims to know Him will enter the kingdom of heaven, but only those who fulfill the will of the Father. This teaching indicates that mere acknowledgment or verbal affirmation of Christ is insufficient for salvation. It is the embodiment of faith through actions—doing God's will—that authenticates a believer's relationship with Him. This aligns with other biblical teachings, such as James 1:22, which emphasizes the necessity of being doers of the Word, evidencing true faith through actual obedience.