Acts 7:51

By rejecting Jesus the Sanhedrin was doing just what their forefathers had done in rejecting God’s other anointed servants, such as Joseph and Moses. They were "stiff-necked," a figure of speech for self-willed. Moses used this expression to describe the Israelites when they rebelled against God and worshipped the golden calf (cf. Exodus 33:5; Deuteronomy 9:13). While Stephen’s hearers had undergone physical circumcision, and were proud of it, they were uncircumcised in their affections and responsiveness to God’s Word. They were resisting the Holy Spirit rather than allowing Him to control (fill) them. They were similar to the apostates in Israel’s past (cf. Leviticus 26:41; Deuteronomy 10:16) whom former prophets had rebuked (cf. Jeremiah 4:4; Jeremiah 9:26). By resisting Stephen, who was full of the Holy Spirit (Acts 6:3; Acts 6:5), they were resisting the Holy Spirit.