There is no physical mark or label that professed Christians carry. So anyone can claim to be a Christian. No laboratory can test the quality and genuineness of what people profess to be. There are people who are genuine Christians but the devil has been whispering into their ears that they are not good enough. The enemy brings all their past evil deeds to their memories and causes them to believe that they cannot be Christians. The enemy would tell them that God is too holy to accept them, their sins are unforgivable, and based on their past, they cannot be "children of God." The enemy has also deceived some people to believe that they can live anyhow they want, and that the physical life they live cannot affect their spiritual life. For people not to be deceived and have assurance of salvation there is the need for self-examination. Examine yourself to see if you are in the faith, test yourselves." To the Christian, self-examination should be a daily routine.