It is conceivable that some have repented of the works of the flesh. Yet they still may be ignorant of the only Name that offers salvation. Scripture says we must seek truth and then walk in all the light we are given, 1John 1:7.
Your question touches on a type of John’s baptism, the baptism unto simple repentance. In Acts 18 is a man named Apollos, an eloquent man “mighty in the Scriptures.” Yet he had still more to learn. Verse 25 says, “This man was instructed in the way of Yahweh; and being fervent in the spirit, he spake and taught diligently the things of Yahweh, knowing only the baptism of John.”
Notice how Aquila and Priscilla furthered his education: “And he began to speak boldly in the synagogue: whom when Aquila and Priscilla had heard, they took him unto them, and expounded unto him the way of Yahweh more perfectly.” (Acts 18:26)
The passage indicates that their instruction included the necessity now to be immersed into Yahshua’s Name.
Then in the next chapter, 19, Paul encounters more disciples who had not heard of baptism into Yahshua’s Name, which is baptism for salvation as well as repentance.
“He said unto them, have you received the Holy Spirit since you believed? And they said unto him, we have not so much as heard whether there be any Holy Spirit. And he said unto them, Unto what then were you baptized? And they said, Unto John’s baptism. Then said Paul, John verily baptized with the baptism of repentance, saying unto the people, that they should believe on him which should come after him, that is, on Messiah Yahshua. When they heard this, they were baptized in the Name of the Master Yahshua.” No questioning, no arguing, just compliance.
When we repent and are baptized into the salvation that comes only in Yahshua’s Name, we are endowed with Yahweh’s Holy Spirit and begin to grow spiritually.
The common titles or names do not provide His salvation. Acts4:12 says, “Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved.” “Yahshua” means “Yahweh is salvation.” Only in the specific Name Yahshua do we find everlasting life.
Speaking of the need for proper immersion, the Savior Himself said, “…for thus it becomes us to fulfill all righteousness.”
If a sincere believer and follower of Truth becomes aware of the true Names that he has been ignorant of, then he must accept, not reject, this truth. Nominal worship long ago effectively cut ties with Israel and the promises Yahweh gave exclusively to those who are grafted into the Israelite promise.