Why is Growth in Godliness Important?

Growth in godliness is the only sure sign of spiritual life.

Supernatural ministry gifts are no sure signs of spiritual life.

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. 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?' And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness (Matt 7:21-23).
Then that lawless one will be revealed…the one whose coming is in accord with the activity of Satan, with all power and signs and false wonders, and with all the deception of wickedness for those who perish, because they did not receive the love of the truth so as to be saved (2Thess 2:8,9).

Growth in holy obedience is the only sure sign of spiritual life.

"Beware of the false prophets, who come to you in sheep's clothing, but inwardly are ravenous wolves. You will know them by their fruits. Grapes are not gathered from thorn bushes nor figs from thistles, are they? So every good tree bears good fruit, but the bad tree bears bad fruit. A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. So then, you will know them by their fruits (Matt 7:15-20).
Someone said to Him, "Behold, Your mother and brothers are standing outside seeking to speak to you." But Jesus answered the one who was telling Him and said, "Who is My mother and who are My brothers?" And stretching out His hand toward His disciples, He said, "Behold My mother and My brothers! For whoever does the will of My Father who is in heaven, he is My brother and sister and mother" (Matt 12:47-48).