Acts 18:6

‘And when they opposed themselves and blasphemed, he shook out his raiment and said to them, “Your blood be on your own heads. I am clean. From now on will go to the Gentiles.” '

The consequence of this powerful preaching of the word was that ‘the Jews' (those who refused to believe) reacted by blaspheming against it. This probably indicates their refusal to accept Christ as the Messiah and being insulting about Him. And the final result was that he deserted the synagogue, shook off its dust from his clothes as a testimony against them, and declared that he was leaving them in order to go the Gentiles outside the synagogue (compare Nehemiah 5:13; Matthew 10:14). Of course once he did so he would be even more persona non grata in the synagogue.

‘Your blood be on your own heads.' Compare 2 Samuel 1:16; Ezekiel 33:6. Paul no longer considers himself responsible for them. 2 Samuel 1:16, which contains the more exact parallel, was spoken of one who had ‘slain the Lord's anointed'. The implication may therefore be that by their blasphemy against Christ he considers that they have crucified Him again (compare Hebrews 6:6).

We may probably gather from this that the response from the God-fearers had been very different from that of the Jews, and that they had begun to bring Gentile friends to hear Paul. That may well have been part of the reason for the opposition.