In the Philocalia of Origen XVI, §1, which passage is drawn from his Contra Celsum, Origen considers the apparent scandal of the preponderance of Christian sects. There were then, just as in our own times, various different groups of Christians which differed among themselves with respect to some teachings. What they had in common, says Celsus rather naïvely, was only the name of "Christian." But their divisions and differences were, at least for some nonbelievers, a point in their disfavor.
Origen's response to this problem, at least the first part thereof, is an interesting and intelligent one. He notes that people are liable to have differences of opinion, and these differences may become heated and sharp, when they concern some matter of importance. Origen gives the following examples. Just as the health of the body and its treatment is a very important thing for the human race, so also various thoughtful doctors differed in that time amongst themselves and form different sects. So also there was a great number of philosophical schools, all of whom differed on how to define and live a good human life.
Origen argues that it would be foolish and unwarranted to reject the practice of medicine and healthcare simply because there are different sects of doctors. Likewise, philosophy can't rightly be ignored or abandoned simply because philosophers differ among themselves; the subject matter is too lofty and important to be treated with such indifference. In the same way, Christian sects differ among themselves because intelligent people were concerned to have a proper and good understanding of the scriptures, considering them to be genuine revelation from God. The divisions, in other words, owe to a sincere desire to know the truth of what God has revealed, rather than perversity or ill will. Of course, not every school can be right; the point is only that the basis of the differences is a sincere and good will.
This is an important reminder for us in times of scandalous and problematic divisions among Christians. Even if we differ one from another, we ought to remind ourselves that our differences arise from a sincere and genuine desire to know God's truth as it has been revealed. We do ourselves no favors in demonizing opponents and hardening our hearts against them, when we want the same thing in the end! This is not to say that there aren't persons of perverse will who do not really have an interest in the truth; but judging whether another person is like that or not is difficult and perilous, and it is perhaps better to assume the best and dialogue with good will when it is fruitful and edifying.