Ye stiff-necked - The discourse of Stephen has every appearance of having been interrupted by the clamors and opposition of the Sanhedrin. This verse has no immediate connection with what precedes, and appears to have been spoken in the midst of opposition and clamor. If we may conjecture in this case, it would seem that the Jews saw the drift of his argument; that they interrupted him; and that when the tumult had somewhat subsided, he addressed them in the language of this verse, showing them that they sustained a character precisely similar to their rebellious fathers. The word “stiff-necked” is often used in the Old Testament, Exodus 32:9; Exodus 33:3, Exodus 33:5; Exodus 34:9; Deuteronomy 9:6, Deuteronomy 9:13; Deuteronomy 10:16, etc. It is a figurative expression taken from oxen that are refractory, and that will not submit to be yoked. Applied to people, it means that they are stubborn, contumacious, and unwilling to submit to the restraints of Law.
Uncircumcised in heart - Circumcision was a sign of being a Jew - of acknowledging the authority of the laws of Moses. It was also emblematic of purity, and of submission to the Law of God. The expression “uncircumcised in heart” denotes those who were not willing to acknowledge that Law, and submit to it. They had hearts filled with vicious and unsubdued affections and desires.
And ears - That is, who are unwilling to “hear” what God says. Compare Leviticus 26:41; Jeremiah 9:26. See the notes on Romans 2:28-29.
Resist the Holy Ghost - You oppose the message which is brought to you by the authority of God and the inspiration of his Spirit. The message brought by Moses; by the prophets; by the Saviour; and by the apostles - all by the infallible direction of the Holy Spirit - they and their fathers opposed.
As your fathers did ... - As he had specified in Acts 7:27, Acts 7:35, Acts 7:39-43.