The sneering classes would undoubtedly say that such a claim from Scripture is merely to be expected and lacks external evidence. There was perhaps a time when I would have agreed with them.
There is a way, however, whereby proof of this Truth may readily be encountered.
Accept the Living Lord into your own life by repenting your sin; accept that His blood at Calvary cleanses you; agree to follow Him for the remainder of your life.
Do this sincerely; thank Him daily; pray unceasingly and you will come to KNOW His truth - not as an opinion - but as a total certainty.
Christian or no, if you do not have this in your life - it is time, this Easter, for a complete, spiritual overhaul. Back to basics!
