Hello. It is certainly the case that most Jews back then thought the Good News was nutty (to put it mildly - consider how the 'pre-Damascus' Paul acted!). My point is just that there was no one Judaism (Pharisees, Essenes, Sadducees, etc.) so, IMHO, the first Christians were really just another Jewish sect. And consider that James, the brother of Jesus, seems to have remained very respected in Jerusalem, attending temple, right up until the destruction in 70 AD (and was the real power broker, if you will, among the early Christians as we read in Acts).
Peace