15 “Beware of the false prophets, who come to you in sheep’s clothing, but inwardly are ravenous wolves. 16 You will know them by their fruits. Grapes are not gathered from thorn bushes nor figs from thistles, are they? 17 So every good tree bears good fruit, but the bad tree bears bad fruit. 18 A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. 19 Every tree that does not bear good fruit is cut down and thrown into the fire. 20 So then, you will know them by their fruits. 21 “Not everyone who says to Me, ‘Lord, Lord,’ will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter. 22 Many will say to Me on that day, ‘Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles? ’ 23 And then I will declare to them, ‘I never knew you; depart from ME, you who practice lawlessness.'”(Matthew 7:15-23 NASB)
Christian authenticity is a set of marks of genuineness. Christ said that we can tell false Christians from real Christians by their fruit. There is fruit that real Christians produce that false Christians cannot. Even those who are in the fires of tribulation, fighting deadly battles against their sin nature will be growing in these areas. Their visible fruit may be small or even embryonic, but it will be there. However, the false believer, since he or she has not the Holy Spirit nor are they regenerate, cannot bear this fruit. It grows only in the hearts of those God has touched with His grace unto the New Birth.