Jesus said that many who call Him Lord do not actually know Him, because they are not obeying Him (Matt. 7;21-23). How can we be assured that we truly know God? He tells us that if we love people and obey His commands, we will know Him.
1 John 4:7
Everyone who loves is born of God and knows God.
2 John 6
This is love, that we walk according to His commandments. This is the commandment, that as you have heard from the beginning, you should walk in it.