Origen

“ Let us not therefore suppose that it is a trivial sin to mind the things of men, since we ought in everything to mind the things of God. And it will be appropriate also to say this to every one that has fallen away from the doctrines of God and the words of the church and a true mind; as, for example, to him who minds as true the teaching of Basilides, or Valentinus, or Marcion, or any one of those who teach the things of men as the things of God. ”

“ But, so far as it depends on himself, he who says or does such things is a stumbling-block even to him who will not be offended; unless perhaps Jesus calls the disciple who sinned a stumbling-block even to Himself, as much more than Paul He would have said from love, “Who is weak, and I am not weak? Who is made to stumble, and I burn not?” ”