Paul not debating, not disputing, not in contention, Paul teaching no divisions, but to be of the same mind and judgement.How could the Corinthians believers "realize that Paul did not fail the test of being in the faith" if they couldn't judge whether or not he was? Well, as the indicators I listed above (and many others in Scripture that I didn't) reveal, no one ever has to be uncertain about their born-again status. And they can apply the same biblical criteria to the born-again claims of others. This would be necessary to what Paul, Peter, John and James all did in their letters, distinguishing false believers from real ones.
2 Corinthians 11:26
26 I have been on frequent journeys, in dangers from rivers, dangers from robbers, dangers from my countrymen, dangers from the Gentiles, dangers in the city, dangers in the wilderness, dangers on the sea, dangers among false brethren;
1 Corinthians 1:10 Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye ALL SPEAK THE SAME THING, and that there be NO DIVISIONS AMONG YOU; but that ye be PERFECTLY JOINED TOGETHER IN THE SAME MIND AND IN THE SAME JUDGMENT.
11 For it hath been declared unto me of you, my brethren, by them which are of the house of Chloe, that there are CONTENTIONS among you.
12 Now this I say, that every one of you saith, I am of Paul; and I of Apollos; and I of Cephas; and I of Christ.
13 IS CHRIST DIVIDED? was Paul crucified for you? or were ye baptized in the name of Paul?
1 Timothy 6:3 If any man teach otherwise, AND CONSENT NOT TO WHOLESOME WORDS, even the words of our Lord Jesus Christ, and to the doctrine which is according to godliness;
4 HE IS PROUD, KNOWING NOTHING, but doting about questions and STRIFES OF WORDS, whereof cometh envy, strife, railings, evil surmisings,
5 PERVERSE DISPUTINGS OF MEN OF CORRUPT MINDS, and destitute of the truth, supposing that gain is godliness: from such withdraw thyself.