Saying "I'm not going to do your homework for you" cripples your own argument, since you cannot reasonably refuse to define a term which you yourself introduced into the discussion.
"Get these books (Schaff and Sullivan)"? --- You, the 'sola scriptura' guy, are referencing something not found in any New Testament concordance (the term 'house church') by writers not found in Scripture (Schaff and Sullivan)? So why should I use those books as my authority? They're not Scripture.
You'e either going to have to define and defend it from Scripture alone, or abandon the un-Biblical doctrine of "Scripture alone."
The Word of God is the sole rule of Faith --- on this we both agree --- but the Word of God is more than just what was put into writing in the God-inspired books: more than Scripture alone.
John's Gospel ends with these words: "Jesus did many other things as well. If every one of them were written down, I suppose that even the whole world would not have room for the books that would be written."
So Jesus, who is the Word of God, did and said and taught more than what was written. That's why He promised the Holy Spirit to guide the apostles to "all truth" (Jn 16:13). "But the Counselor, the Holy Spirit, whom the Father will send in my name, he will teach you all things, and bring to your remembrance all that I have said to you" (John 14:26).
Otherwise, he would have just said, "Get the book."
If the written Word alone were all that's needed, God need not have sent his Son, and we'd be reading "God so loved the world, that He sent His Son oops, His Book."
And there'd be no need for the Son to send the Holy Spirit; that passage from John 14:26 would read, "But the Holy Spirit oops, the Holy Book, which the Father will send, will teach you all things."
And at no point does the Bible itself call the Bible alone "the pillar and foundation of the truth."
You miss the third option.
Don't purse discussions with those that go out of their way to mix subjects and in the process misrepresent the original point, such as your statement above.