You know what else can REALLY challenge your faith?
Take a little walk through church history! Yikes. For instance, how we decided on the doctrine of the Trinity. For a while there, it was a matter of whose monks beat up the other guy's monks. I think Arian got a bum rap. You want to read an interesting portrayal of the characters and times I highly recommend When Jesus Became God: The Epic Fight over Christ's Divinity in the Last Days of Rome.
This is where Cyril comes in. You can find more detailed histories of him elsewhere. What I find interesting about Cyril was how he was in the middle of the Trinitarian debate. You may have read in your simple Christian history that the question of the Trinity was solved at the Council of Nicea in 324. No no no. The Arians went on as though nothing happened and even those who signed on started having second thoughts. Bishops were excommunicated and exiled depending on who was emperor and who could get his ear. Cyril, in trying to find a way to formulate the doctrine in a way all sides would find acceptable, found himself exiled three times! Once by the Athanasius crowd and twice by the Arians. See that's what you get for trying to please everyone. You end up with everyone pissed off at you. So you might as well just take a stand and at least one side will be with you! That's what Cyril finally did and chose the winning side and voted for the Nicean formula at Council of Contstanople in 381.
Cryil did some other stuff that got him canonized and we still have his Catechetical Lectures as well as liturgical forms that were used for many years.
I think it is so important that we know our church history, even if it is a little disillusioning. We learn that things are not that different now. There never has been a "Golden Age" when the church was one and everyone agreed. When we aren’t persecuted from the outside, we are making trouble among ourselves. And yet the Holy Spirit “calls, gathers, enlightens an sanctifies the whole Christian church on earth and keeps it united with Jesus Christ in the one true faith” (Martin Luther’s explanation to the Apostle’s Creed, Small Catechism)