Doctrinally there is continuity as you suggest, but not dogmatically. The early fathers had only notions of the dogmatic pronoucements of the Church that were to come, and not all of them were in full agreement.
This can be see from your own quote of St. Ignatius to Smyrinians where he says "because they confess not the Eucharist to be the flesh of our Savor Jesus Christ, which suffered for our sins, and which the Father, of His goodness, raised up again."
Here you have both doctrinal agreement and dogmatic disagreement. The agreement is that the Eucharist is the "flesh of our Saviour," but the dogmatic disagreement is in the suggestion that it was the Father (God) who raised him up again [sic].
The Nicene Creed corrects this by stating that Christ rose (himself) on the third day in order to emphasize the equality of the Son with the Father in his divinity. The subordination of the Son is to be found in the NT and as a predominant teaching of early Christian writers which inevitably led to the emergence of Chriostological heresies over time.
By the way, I seriously doubt that the copy of St. Irenaeus's epistle which you quote is genuine since no one before Irenaeus (end of 2nd century) quotes from any of the NT books by author's name (and verse numbers were not used). So, while the words of Matthew 19:12 would be very likely in his writings, the reference reference is not.
You also have to understand that the authenticity of Ignatius' seven (ah, that magical number!) letters is based on the testimony of none other than Eusebius of Cesarea, the first Church historian whose credibility is questioned or affirmed by people pretty much as they feel on that day, and that all of St. Ignatius' letters are latter-day copies which have, like all ancient documents, been altered and redacted by copyists pretty much as they saw fit.
Another example of dogmatic issues among early fathers is St. Irenaeus, who called Mary advocata (based on the only surviving complete copy of his work being a Latin translation from AD 380). Translated back into Greek, it means Paraclete. I don't have to tell you what sorts of problems this invokes, especially knowing that many thought of the Holy Spirit as being feminine.
This unfortunate reference is naturally shoved under the carpet and not talked about when we speak of St. Irenaeus' orthodoxy in other matters.
You both make interesting points...but I’m out of time today, and will be out of town tomorrow. I’ll think about them some, and try to figure out a response by next week.
The trinitarian dogma was fully developed in 4c, so naturally St. Ignatius relies on the Gospel texts alone, which, regarding His divinity, can be read in a variety of ways. This is not a disagreement -- unless you are prepared to say that the Gospels are in disagreement with 1st Nicea. Is is undeveloped doctrine, and continuity of doctirnal development.
authenticity
I will not participate in discussions of authenticity based on which copes of what survived. This approach is waste of time.
called Mary advocata
Mary is sometimes called Advocate today, so again there is no discontinuity in that. I also had to hire a lawyer not long ago, and were I speaking to him in any of many languages other than English, I'd call him advocate, because that is what "advocate" means.