Well, let's add St. Cyril of Jerusalem to the mix as well. Writing catechetical notes in 350, St. Cyril pretty much hammers the belief in the True Presence home:
Even of itself the teaching of the Blessed Paul is sufficient to give you a full assurance concerning those Divine Mysteries, of which having been deemed worthy, ye are become of the same body. For you have just heard him say distinctly, That our Lord Jesus Christ in the night in which He was betrayed, took bread, and when He had given thanks He brake it, and gave to His disciples, saying, Take, eat, this is My Body: and having taken the cup and given thanks, He said, Take, drink, this is My Blood Since then He Himself declared and said of the Bread, This is My Body, who shall dare to doubt any longer? And since He has Himself affirmed and said, This is My Blood, who shall ever hesitate, saying, that it is not His blood?
My translation (Jurgens) is a little different, but you can hardly walk away from this statement thinking that Early Christians didn't believe in the Real Presence.
Another point is prayers for the dead. Catholics support this Tradition using a scripture that Protestant churches don't recognize (2 Maccabees 12:43–45). However, again, since this aspect of Catholic Worship predates claims of Purgatory's fabrication by Pope St. Gregory, something has to give. In this passage, St. Cyril talks about the prayers for the dead offered during the Eucharistic prayer:
And I wish to persuade you by an illustration. For I know that many say, what is a soul profited, which departs from this world either with sins, or without sins, if it be commemorated in the prayer? For if a king were to banish certain who had given him offence, and then those who belong to them should weave a crown and offer it to him on behalf of those under punishment, would he not grant a remission of their penalties? In the same way we, when we offer to Him our supplications for those who have fallen asleep, though they be sinners, weave no crown, but offer up Christ sacrificed for our sins, propitiating our merciful God for them as well as for ourselves.
That Church Fathers area a treasure for the Church, and a bulwark against false doctrine.