This is how we know that we know him: if we keep his commandments.
Now, if I say I believe in Jesus Christ as my Lord and my Savior, then that very belief is going to bring about a certain style and manner of living. If I really believe it. Now, I can say I believe something that I don't really believe. And I may fool people into thinking that I believe something that I don't really believe, but I don't fool God. For true belief in Jesus Christ is going to be manifested my behavior. I cannot walk in darkness and possess the light.