Initially, the believers were believing and preaching the ‘same’ truth & then came those who offered ‘alternate views of Christianity’:

“You were running well; who hindered you from obeying the truth? This persuasion did not come from Him who calls you. A little leaven leavens the whole lump of dough.” – apostle Paul (Galatians 5:7 – 9, NASB)

Yes, apostle Paul Warns against those who preach a “different view” from ‘what he preached’ with regards to the Gospel:

“I have confidence in you in the Lord that you will adopt no other view; but the one who is disturbing you will bear his judgment, whoever he is.” – apostle Paul (Galatians 5:10, NASB)

The warning in the last verse above is ‘serious’ and that’s why we strive to follow & believe apostle Paul’s Inspired Writings instead of ‘our feelings or heart or opinions which are self-interest focused, and hence unreliable’.

Indeed, ‘our hearts are unreliable’ especially in ‘deciding truth’:

“The heart is deceitful above all things, and desperately wicked: who can know it?” (Jeremiah 17:9, NASB)

Here are other similar warnings from apostle Paul toward those Christians who teach ‘differently’ from ‘what he preached’ (the ‘only endorsed Biblical yardstick’ is apostle Paul for Gentile believers as 1 Corinthians 11:1 clearly mentions):

“I wish that those who are troubling you would even mutilate themselves.” – apostle Paul (Galatians 5:12, NASB)

“But even if we, or an angel from heaven, should preach to you a gospel contrary to what we have preached to you, he is to be accursed (anathema)!” – apostle Paul (Galatians 1:8, NASB)

The fact that apostle Paul writes the same warning again after writing the above in consecutive verses should alert us the ‘seriousness’ of ‘preaching differently than apostle Paul’s Inspired Writings’:

“As we have said before, so I say again now, if any man is preaching to you a gospel contrary to what you received, he is to be accursed (anathema)!” – apostle Paul (Galatians 1:9, NASB)

“Now I urge you, brethren, keep your eye on those who cause dissensions and hindrances contrary to the teaching which you learned, and turn away from them.” – apostle Paul (Romans 16:17, NASB)

“Now we command you, brethren, in the name of our Lord Jesus Christ, that you keep away from every brother who leads an unruly life and not according to the tradition which you received from us.” – apostle Paul (2 Thessalonians 3:6, NASB)

“If anyone does not obey our instruction in this letter, take special note of that person and do not associate with him, so that he will be put to shame.” – apostle Paul (2 Thessalonians 3:14, NASB)

“As I urged you upon my departure for Macedonia, remain on at Ephesus so that you may instruct certain men not to teach strange doctrines,” – apostle Paul (1 Timothy 1:3, NASB)

“If anyone advocates a different doctrine and does not agree with sound words, those of our Lord Jesus Christ, and with the doctrine conforming to godliness,

he is conceited and understands nothing; but he has a morbid interest in controversial questions and disputes about words, out of which arise envy, strife, abusive language, evil suspicions,

and constant friction between men of depraved mind and deprived of the truth, who suppose that godliness is a means of gain.” – apostle Paul (1 Timothy 6:3 – 5, NASB)

“If anyone thinks he is a prophet or spiritual, let him recognize that the things which I write to you are the Lord’s commandment. But if anyone does not recognize this, he is not recognized.” – apostle Paul (1 Corinthians 14:37 – 38, NASB)

“Reject a factious man after a first and second warning,” – apostle Paul (Titus 3:10, NASB)

“If anyone does not obey our instruction in this letter, take special note of that person and do not associate with him, so that he will be put to shame.” – apostle Paul (2 Thessalonians 3:14, NASB)

“So, he who rejects this is not rejecting man but the God who gives His Holy Spirit to you.” – apostle Paul (1 Thessalonians 4:8, NASB)

Yes, we are to follow apostle Paul ‘only’ as a ‘gentile believer’ (because as the ‘apostle of the Gentiles’, his New Testament Inspired Writings apply to ‘every Gentile believer’):

“Brethren, join in following my example, and observe those who walk according to the pattern you have in us.” – apostle Paul (Philippians 3:17, NASB)

“Be imitators of me, just as I also am of Christ.” – apostle Paul (1 Corinthians 11:1, NASB)

“If anyone thinks he is a prophet or spiritual, let him recognize that the things which I write to you are the Lord’s commandment.” – apostle Paul (1 Corinthians 14:37, NASB)

“Finally then, brethren, we request and exhort you in the Lord Jesus, that as you received from us instruction as to how you ought to walk and please God (just as you actually do walk), that you excel still more.

For you know what commandments we gave you by the authority of the Lord Jesus.” – apostle Paul (1 Thessalonians 4:1 – 2, NASB)

Yes, even ‘speaking the SAME thing’ as ‘apostle Paul did’:

“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.” – apostle Paul (1 Corinthians 1:10, KJV)

Because every Gentile will be judged by ‘my Gospel’ (referring to the Gospel delivered to apostle Paul only):

“For when Gentiles who do not have the Law do instinctively the things of the Law, these, not having the Law, are a law to themselves,

in that they show the work of the Law written in their hearts, their conscience bearing witness and their thoughts alternately accusing or else defending them,

on the day when, according to my gospel, God will judge the secrets of men through Christ Jesus.” – apostle Paul (Romans 2:14 – 16, NASB)

Conclusion (in Principle)

“Whoever then shall break one of the least of these commandments and shall teach others the same, he will be called least in the kingdom of the heavens; but whoever shall keep and shall teach them, he will be called great in the kingdom of the heavens.” – Lord Jesus Christ (Matthew 5:19, BLB)

P/S:

“for God is not a God of confusion but of peace, as in all the churches of the saints.” – apostle Paul (1 Corinthians 14:33, NASB)

“But if one is inclined to be contentious, we have no other practice, nor have the churches of God.” – apostle Paul (1 Corinthians 11:16, NASB)

God never changes His Laws within a Covenant for an age. It holds till the end of that age just like it did for the Old Covenant during the Previous ‘age’:’

“My covenant I will not violate, Nor will I alter the utterance of My lips.” – God (Psalm 89:34, NASB)

“When He [God] said, “A new covenant,” He has made the first obsolete. But whatever is becoming obsolete and growing old is ready to disappear.” – Unknown (Hebrews 8:13, NASB)

Can we see it?