Stiffnecked (sklērotrachēloi). From sklēros (hard) and trachēlos, neck, both old words, but this compound only in the lxx and here alone in the N.T. Critics assume that Stephen was interrupted at this point because of the sharp tone of the speech. That may be true, but the natural climax is sufficient explanation.
Uncircumcised in heart (aperitmētoi kardiais). Late adjective common in lxx and here only in the N.T. Verbal of peritemnō, to cut around and a privative. Both of these epithets are applied to the Jews in the O.T. (Exo 32:9; Exo 33:3, Exo 33:5; Exo 34:9; Lev 26:41; Deu 9:6; Jer 6:10). Kardiais is locative plural like ōsin (ears), but some MSS. have genitive singular kardias (objective genitive). No epithet could have been more galling to these Pharisees than to be turned “uncircumcised in heart” (Rom 2:29). They had only the physical circumcision which was useless.
Ye always (humeis aei). Emphatic position of humeis and “always” looks backward over the history of their forefathers which Stephen had reviewed.
Resist (antipiptete). Old word to fall against, to rush against. Only here in the N.T., but used in the O.T. which is here quoted (Num 27:14). Their fathers had made “external worship a substitute for spiritual obedience” (Furneaux). Stephen has shown how God had revealed himself gradually, the revelation sloping upward to Christ Jesus. “And as he saw his countrymen repeating the old mistake--clinging to the present and the material, while God was calling them to higher spiritual levels--and still, as ever, resisting the Holy Spirit, treating the Messiah as the patriarchs had treated Joseph, and the Hebrews Moses--the pity of it overwhelmed him, and his mingled grief and indignation broke out in words of fire, such as burned of old on the lips of the prophets” (Furneaux). Stephen, the accused, is now the accuser, and the situation becomes intolerable to the Sanhedrin.