Read the following passage from Paul's letter to the church at Philippi, in western Macedonia, while he was imprisoned in Rome in 62 CE.
1 Finally, my brothers, rejoice in the Lord...
2 Look out for the dogs, look out for the evildoers, look out for those who mutilate the flesh.
3 For we are the real circumcision, who worship by the Spirit of God and glory in Christ Jesus and put no confidence in the flesh.
In this passage, Paul really does seem to identify the "circumcised in the flesh" with "dogs." For now, let's just note that the association among Christians of the practice of Judaism with bestial, subhuman qualities came very early.