Tell that to James, and Paul...
Acts 21:24 Them take, and purify thyself with them, and be at charges with them, that they may shave their heads: and all may know that those things, whereof they were informed concerning thee, are nothing; but that thou thyself also walkest orderly, and keepest the law.
Acts 21:26 Then Paul took the men, and the next day purifying himself with them entered into the temple, to signify the accomplishment of the days of purification, until that an offering should be offered for every one of them. 21:27 And when the seven days were almost ended, the Jews which were of Asia, when they saw him in the temple, stirred up all the people, and laid hands on him,
Acts 24:16 And herein do I exercise myself, to have always a conscience void of offence toward God, and toward men. 24:17 Now after many years I came to bring alms to my nation, and offerings. 24:18 Whereupon certain Jews from Asia found me purified in the temple, neither with multitude, nor with tumult. 24:19 Who ought to have been here before thee, and object, if they had ought against me.
Why did James and "thousands of Jews which believe" still practice that?
You don't know; do you?
Why did Paul?
Why did Peter still preach it?
