Hi,
If your friend challenges you with other early Christian writers who sound a bit “off”, here are a couple of points to keep in mind. (Apologies in advance for wordiness. I can’t stop myself…)
In the first few centuries of the Church, doctrines such as the Trinity, or the relationship of Christ’s divine and human natures, were only beginning to be understood, and the writings of many early Christians do contain a variety of opinions, some of which we would recognize today as wrong. Different doctrines were thought about and debated for several centuries, and from time to time the Church had to make decisions about what to believe, and what words should be used to describe it. They put their final versions into the creeds, e.g. the Nicene Creed from the first Council of Nicaea (A.D. 325), and from that time on the doctrines they contain have been binding on all Christians.
The point about this is that there is nothing unsettling in reading something in an early Church Father which is obviously contrary to what Catholics believe today. It is just evidence for the many opinions that existed at that time. Scripture has always been interpreted in different ways to support different views, and for some things the Church took its time about deciding which ones were correct.
It’s the same with the many early gospels and writings about Jesus that are not part of the New Testament. The Church as a whole discerned which gospels were inspired and should be read as scripture, and this also took a long time.
Many protestants believe in the New Testament canon, the doctrine of the Trinity and the concept that the one Person of Christ includes both a divine and a human nature, without realizing that these were not taught in the form we now have them right from the start. In fact it was the Church after the apostles’ time that defined and established them after a long process of reflection, debate and discernment, and it could do this because of the authority it has from God, and according to His promise that Christ would never leave it and the Holy Spirit would guide it into all truth. Just because an author is early, doesn’t mean that everything he wrote is right.
Non-orthodox groups which derive from protestantism [Mormons, Jehovah’s Witness, Seventh Day Adventist] all vary from the Creeds in some ways, and they justify their beliefs by using both scripture and early Church writings. Sometimes their interpretation of a passage of scripture and the false doctrine they claim it proves sound clear and reasonable, and this can be confusing and even alarming. But the blessing of being a Catholic is that we can respond by acknowledging freely that yes, a certain early writer did write something that would now be called heresy, or yes, this passage of scripture could be used to support a false doctrine. BUT THEN we point out that this doesn’t matter, because we believe the interpretations and doctrines which the Church has decided on and declared to be true.
Sometimes people will criticize this position as putting the Church above Scripture, implying that we don’t believe that the Bible is the inspired word of God. This is not correct. We do believe in the inspiration of Scripture, and we also believe that God has given us the Church is its authorized interpreter, so its explanations and doctrines are the ones we should believe, and we do not have to be confused by all the other possible ones.
I hope this helps…
