Adam Clarke on Acts 15:9

Put no difference between us and them - Giving them the Holy Spirit, though uncircumcised, just as he had given it to us who were circumcised: an evident proof that, in the judgment of God, circumcision was no preparation to receive the Gospel of Christ. And as the purification of the heart by the Holy Spirit was the grand object of the religion of God, and that alone by which the soul could be prepared for a blessed immortality, and the Gentiles had received that without circumcision, consequently, the shadow could not be considered of any worth, now the substance was communicated.