How to Know that Christ Is In Your Life

Did you receive Christ into your life? According to His promise in Revelation 3:20 ([Christ speaking] "Behold, I stand at the door and knock; if anyone hears My voice and opens the door, I will come in to him"), where is Christ right now in relation to you? Christ said that He would come into your life. Would He mislead you? On what authority do you know that God has answered your prayer? (The trustworthiness of God Himself and His Word.)