NOTES for Act 4:1-22
The statement that the healed man had been healed in the name of Jesus was quite bold. The fact is that, when sacred names were involved, Yahwists in general and Jews in particular had always been quite cautious. In Judaism this caution reached the point that the name Yahweh, for example, was forbidden to be pronounced aloud at all, so that no one would accidentally say it in vain and thereby violate the third commandment of the Decalogue. And if we speak of healing, healing was possible only by God's name. The statement that healing was possible in the name of Jesus in effect meant that His name was being equated with God's name and included among the sacred names. Of course, the name "Jesus" or, more precisely, "Yeshua," includes the name Yahweh, but everyone understood that this was not the point. That is why the representatives of the temple elite were concerned. By speaking of healing in the name of Jesus, the apostles were thereby in effect declaring not only Jesus' messiahship, but also His divinity, however they understood it.
They were publicly declaring that one could appeal to Jesus just as one appeals to God. There was something here to think about. Of course, the concept of the sacred in Yahwism, and therefore in Judaism, was broad enough; it was connected with the concept of theophany, of God's manifestation, and the sacred names themselves were sacred precisely in this sense: invoking them was connected with theophany, with God's manifestation.
Still, no holy thing could replace God as the source and condition of all holiness. To speak of the name of a man, even if that man was the Messiah, as a sacred name was something new and unprecedented. This question required, at the very least, serious discussion. Yahwism, and later Judaism, had a calm enough attitude toward various views and theological theories, and Jewish tradition knows the most unusual and unexpected interpretations of the Torah and theological concepts.
Practice was another matter, especially prayer practice: here Judaism had always been quite conservative and cautious. But such conservative caution was foreign to the apostles. That is understandable: they were not learned rabbis and interpreters of the Torah, but witnesses of what they had seen with their own eyes. God had revealed to them what He had revealed, and for them not to bear witness to the revelation would have meant not listening to God, preferring people to Him. The apostles, of course, could not do that. Conflict with the Temple and the Sanhedrin became unavoidable.