I’m not too sure. According to Gamaliel, if they weren’t of God, they would disappear like the previous movements. Seeing that they don’t, perhaps there is something else at play? Each movement seems to possess truth that the others don’t possess. It looks like another blind men and elephant situation. As to how or why God allows churches to fall to blindness and caprice of men, I have no clue. Even true prophets fall into not seeing the bigger picture. In Romans 11, Elijah talks to God, and claims to be the only one left to loyally serve. However, God retorts that he still had 7000 men that Elijah wasn’t aware of.
Moreover, let’s say we have Trinitarians. But some of them espouse the salvation and restoration of the entire cosmos, as opposed to merely the church, through the blood of Jesus the Christ (Colossians 1:19; Acts 20:28). In 2 Peter, 3:10, the Earth and its works will be found/disclosed, as opposed to burnt up.
@LeeB, perhaps you are right that Gamaliel’s passage does not apply. Tangentially, this reminds me of Philippians 1:15-18:
15 It is true that some preach Christ out of envy and rivalry, but others out of goodwill. 16 The latter do so out of love, knowing that I am put here for the defense of the gospel. 17 The former preach Christ out of selfish ambition, not sincerely, supposing that they can stir up trouble for me while I am in chains.18 But what does it matter? The important thing is that in every way, whether from false motives or true, Christ is preached. And because of this I rejoice.
@LeeB. I know this is talking about motives, and not methods. I know there are errors in definition and even methodology, but honest errors do happen, particularly in the case of 2 Peter 3:10, when later manuscripts were used, instead of earlier. The later scribes may have had bad motives, but we can’t blame the later readers for perpetuating the error.
Still more, during the reign of King Josiah of Judah, he had to dig up the old Temple just to recover lost scripture. Can you blame the generations immediately preceding him, bereft of such teachings and instructions?