These are they who separate themselves, sensual, having not the Spirit.
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Aquinas Study Bible
AD 2017
Here was see yet another crime which these awful heretics have committed. Not only are they perishing themselves, they have raided the Church and taken people away from it, which means that they have taken them outside the faith into their own assemblies. (Oecumenius)
Those, he says, separating the faithful from the unfaithful, be convicted according to their own unbelief. And again those separating from the flesh. He says, Animal not having the spirit; that is, the spirit which is by faith, which supervenes through the practice of righteousness.