These four verses could be almost all a Christian needs to know to be a complete, informed follower of Christ. It provides a description of the saved Christian: 1) How we can know we are His. 2) How we can tell if we are lying about it or tell if the truth is not in us. 3) The means (to again) know we are in Him. 4) What this ought to actually look like in the life of the true believer.