There simply is no outward mark. Signs, as walking after one’s own experience after the flesh are for those who believe not. The kingdom of God is not of this world .Never was never will be.
That sign for the rebellious (no faith) was fulfilled at Pentecost when God interpreted His langue as prophecy in other languages, as prophecy. Tongues are both a sign for the lost, and prophecy for those who believe God according to the faith of God, as it is written .
This is other than His interpretation to the Jews who did believe just as the gentiles at Pentecost he put no difference between the two purifying the hearts of both by a work of His faith as a labor of his great love and mercy. . . The words He put on Peters tongue worked in the same way He put his words on Balaam’s donkey tongue as a work of His faith, working in the creatures. Not of, coming from the creatures.
Isa 28:11 For with stammering lips and another tongue will he speak to this people
The apostate Jews walked after their own experiences hoping in their own flesh , called walking by sight having it in respect to a ceremonial work they performed. This is again is as
if the kingdom of God was of this world and did not belong to the god of this corrupted world, Satan.
The Gentiles walked or understood after the intellect of the philosophies( of sinful men as oral traditions, commandments of men , having their faith in respect to their own dead consciences that cannot produce the faith of Christ but they rather had His faith in respect to their own selves. Therefore making the wisdom of God to no effect.
Christ said it is an evil generation that seeks after as sign of what they ceremonial perform as a work.
For the Jews require a sign, and the Greeks seek after wisdom:But we preach Christ crucified, unto the Jews a stumblingblock, and unto the Greeks foolishness;But unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God. 1Co 1:22
Again they walked after their own experiences, in sight of them, through the ceremonial laws that clearly did nothing to make their consciences /hearts complete, but were mere shadows used until the time of reformation. They did not walk by the faith of Christ, hearing the voice of the Holy Spirit.
It why He said to them in Joh 5:39, they searched the scriptures and saw the history of a Jew that was used as a parable pointing to the eternal not seen (the faith principle). Until the time of reformation.
Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.And ye will not come to me, that ye might have life. Joh 5:39
They came and placed their faith coming from their own hearts in the ceremonial laws, as a work they could do. In the same way as Josef Prince today walking by sight . And therefore not after Christ the Holy Spirit of God, according to His work of faith which works in the believer to both will and do His good pleasure as an imputed righteousness. .
2Corinthians 5:7 (For we walk by faith, not by sight
And that faith above is of Christ, it is not of our own self after our experiences.(walking by sight) There simply is no out ward sign . There is a inward sign of a contrite heart made new thorough Christ, the incorruptible seed that desires we do His good will. It is his witness that witnesses to our new spirits that we have been born again.