“”You stiffnecked and uncircumcised in heart and ears! You always resist the Holy Spirit; as your fathers did, so do you.”
— Acts 7:51 (NKJV)
The description Stephen used to condemn Israel for unbelief and disobedience were commonly used by old testament prophets
Lev 26 (NKJV)
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⁴¹ and that I also have walked contrary to them and have brought them into the land of their enemies; if their uncircumcised hearts are humbled, and they accept their guilt—
⁴² then I will remember My covenant with Jacob, and My covenant with Isaac and My covenant with Abraham I will remember; I will remember the land.
Jer 4 (NKJV)
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³ For thus says the Lord to the men of Judah and Jerusalem: “Break up your fallow ground, And do not sow among thorns.
⁴ Circumcise yourselves to the Lord, And take away the foreskins of your hearts, You men of Judah and inhabitants of Jerusalem, Lest My fury come forth like fire, And burn so that no one can quench it, Because of the evil of your doings.”
“To whom shall I speak and give warning, That they may hear? Indeed their ear is uncircumcised, And they cannot give heed. Behold, the word of the Lord is a reproach to them; They have no delight in it.”
— Jer 6:10 (NKJV)
Jer 9 (NKJV)
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²³ Thus says the Lord: “Let not the wise man glory in his wisdom, Let not the mighty man glory in his might, Nor let the rich man glory in his riches;
²⁴ But let him who glories glory in this, That he understands and knows Me, That I am the Lord, exercising lovingkindness, judgment, and righteousness in the earth. For in these I delight,” says the Lord.
²⁵ “Behold, the days are coming,” says the Lord, “that I will punish all who are circumcised with the uncircumcised—
²⁶ Egypt, Judah, Edom, the people of Ammon, Moab, and all who are in the farthest corners, who dwell in the wilderness. For all these nations are uncircumcised, and all the house of Israel are uncircumcised in the heart.”
Ezek 44 (NKJV)
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⁷ When you brought in foreigners, uncircumcised in heart and uncircumcised in flesh, to be in My sanctuary to defile it—My house—and when you offered My food, the fat and the blood, then they broke My covenant because of all your abominations.
⁸ And you have not kept charge of My holy things, but you have set others to keep charge of My sanctuary for you.”
⁹ Thus says the Lord God: “No foreigner, uncircumcised in heart or uncircumcised in flesh, shall enter My sanctuary, including any foreigner who is among the children of Israel.
This language was adopted by Paul in
Rom 2 (NKJV)
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²⁵ For circumcision is indeed profitable if you keep the law; but if you are a breaker of the law, your circumcision has become uncircumcision.
²⁶ Therefore, if an uncircumcised man keeps the righteous requirements of the law, will not his uncircumcision be counted as circumcision?
²⁷ And will not the physically uncircumcised, if he fulfills the law, judge you who, even with your written code and circumcision, are a transgressor of the law?
²⁸ For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh;
²⁹ but he is a Jew who is one inwardly; and circumcision is that of the heart, in the Spirit, not in the letter; whose praise is not from men but from God.
Galatians 5
2 Listen! I, Paul, tell you this: If you are counting on circumcision to make you right with God, then Christ will be of no benefit to you.
3 I’ll say it again. If you are trying to find favor with God by being circumcised, you must obey every regulation in the whole law of Moses.
4 For if you are trying to make yourselves right with God by keeping the law, you have been cut off from Christ! You have fallen away from God’s grace.
5 But we who live by the Spirit eagerly wait to receive by faith the righteousness God has promised to us.
6 For when we place our faith in Christ Jesus, there is no benefit in being circumcised or being uncircumcised. What is important is faith expressing itself in love.
Where he said unbelieving Jews relied on outward signs rather than transformed hearts. Possibly Paul was influenced by Stephen speech since he was present
Acts7:57 Then they put their hands over their ears and began shouting. They rushed at him
58 and dragged him out of the city and began to stone him. His accusers took off their coats and laid them at the feet of a young man named Saul.
Act 8:1 Saul was one of the witnesses, and he agreed completely with the killing of Stephen.
Act 22:17“After I returned to Jerusalem, I was praying in the Temple and fell into a trance.
18 I saw a vision of Jesus saying to me, ‘Hurry! Leave Jerusalem, for the people here won’t accept your testimony about me.’
19 “‘But Lord,’ I argued, ‘they certainly know that in every synagogue I imprisoned and beat those who believed in you.
20 And I was in complete agreement when your witness Stephen was killed. I stood by and kept the coats they took off when they stoned him.’
21 “But the Lord said to me, ‘Go, for I will send you far away to the Gentiles!’”
But the old testament was more obvious influence.