Matthew 7:21 "Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. 22 On that day many will say to me, 'Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?' 23 And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness.'"
Spiritual activity does not mean we are the Lord's. Even false prophets can do signs and wonders while preaching a wrong message and living an ungodly life (see Deuteronomy 13:1-5; 2 Corinthians 11:4,13-15; 2 Thessalonians 2:9-10). People known by the Lord Jesus Christ are people who have repented of their sin and believed the gospel (Mark 1:15). Saving belief (faith) is characterized by the desire to obey the Lord. The Apostle Paul preached the obedience that comes from faith (Romans 1:5). James preached that even the demons believe and tremble. He preached that faith without works (obedience) is dead. Real faith obeys the Lord (James 2:14-26).
Jesus said that the person who does God's will is the person He knows. If Jesus know us, we have eternal life (John 10:27-28). The first two commands that we are to obey are "repent" and "believe the gospel." We obey these commands by the power of the Holy Spirit. When we believe the gospel, we receive the Holy Spirit and are empowered to obey all the teaching of Jesus (Ephesians 1:13-14, 19-20; 3:20). When we are truly a believer in Jesus Christ, we desire to obey the Lord who loved us by giving His life for us. We obey the Lord by faith in the Son of God, that is, we attempt to do what Jesus teaches us fully expecting Him to fulfill our attempt to obey with His power (Galatians 2:20; 2 Thessalonians 1:11).
What is the test of saving faith? The test is a person's desire to obey the Lord. That desire is revealed by the person learning what Jesus commands us so he/she knows what to obey. Can you pass the test? Does your faith in Jesus give you a desire to learn His commands and obey them by faith?