Let's go back and look at Acts 7, verse 10.
6:10 And they were not able to resist the wisdom and the spirit by which he spake.
Acts 7 Verse 51-54
and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers did, so do ye.
7:52 Which of the prophets have not your fathers persecuted ? and they have slain them which shewed before of the coming of the Just One; of whom ye have been now the betrayers and murderers:
7:53 Who have received the law by the disposition of angels, and have not kept it.
7:54 When they heard these things, they were cut to the heart and they gnashed on him with their teeth.
As I said earlier, they could not resist the HS. The prophets brought them the truth, the Law brought them the truth, the Word brought them the truth, and Jesus brought them the truth. It was the Truth that the HS gave them by different messengers that they rejected and did so by killing the prophets and Jesus, as well as not keeping the Law, which is exactly the rest of Stephen's statement. .
sorry Acts 6:10
Ye stiffnecked and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers [did], so [do] ye. - Acts 7:51