Responding to the second defense of the Dual-Source Theory, let me first repeat the argument:
2. The New Testament writers clearly speak about the importance of Tradition.
2 Thess. 2:15
“So then, brethren, stand firm and hold to the traditions which you were taught, whether by word of mouth or by letter from us.”
Notice the dual sources of the one teaching.
1 Cor. 11:2
“I praise you because you remember me in everything and maintain the traditions just as I passed them on to you.”
This illustrates that traditions (paradosis) are what is being passed on. At the very least, this should help to take the focus off the way in which a tradition is handed down. In other words, the focus is not on written tradition as sola Scriptura advocates tend to believe.
“Dear friends, although I have been eager to write to you about our common salvation, I now feel compelled instead to write to encourage you to contend earnestly for the faith that was once for all entrusted to the saints.”
Notice, the faith was delivered to the “saints.” The “saints” represent a living entity of preservation, not a book, which we know as the Church.
Sola Scriptura response:
The New Testament does speak of the importance of tradition, but the tradition that is referred to in these passages is the Gospel message that was eventually recorded in the New Testament (regula fidei). There is no reason to believe that the New Testament writers were speaking of some infallible “unwritten Tradition” that was separate from the message of the New Testament and that was to be passed on through an unbroken succession of bishops throughout the ages.
In this sense, “tradition” simply refers to the Gospel message. It was handed down in two forms, as it always has, written and unwritten. But these two forms are not distinct bodies of information, and there is no reason to think that they are. As time goes on, all tradition that is not codified in some form becomes increasingly unreliable (think phone tag). That is why the Gospel message was ultimately preserved in the Apostles’ writing and canonized in the New Testament.
This chart helps illustrate:
Notice here that advocates of sola Scriptura recognize the equal authority of the Apostles unwritten teaching while alive (word of mouth). We also recognize its abiding influence into the first few centuries of the church (though diminishing in reliability). This is why we believe that these teachings were codified in the New Testament canon. Eighty-percent of the New Testament canon (Gospels, Acts, Pauline corpus) were accepted as authoritative by the mid second century, possibly as early as the late first century.
Certainly, various traditions arose in the practice and liturgy of the first few centuries of the early church, but these traditions should not be seen as a prescriptive mandate on how to do church. Neither should they be understood as an equal authority to that of Scripture. There is simply no justification to do so.
Of course the message was “handed to the saints” as it is the saints (Christians) who are responsible for the passing on of the Gospel, not any institutional authority.
Next, I will response to the third argument for the Dual-Source Theory.