As does sola ecclesia, as "one Lord, one faith, one baptism" is itself is interpreted differently by different churches, both as to what theological extent this is to taken and the meaning of each.
Even when restricting sola ecclesia to Catholicism, you have disagreements as to whether the "one Lord' means the Father sends the Spirit or He is sent by both the Father and the Son, and whether "one faith" means under an infallible pope having unhindered universal jurisdiction and power, as well as what most departed Catholics experience (re. purgatorial existence), as well as multiple others aspects of faith , both among RCs and Catholicism at large, including whether chrismation with anointed oil from the apostles is part of the baptismal rite to receive the Holy Spirit, and whether extra Ecclesiam nulla salus means baptized Prots need not repent from sola fide and convert to Catholicism to be saved, and whether baptism of desire is an infallible teaching. Etc.
And the idea of a real depth of unity in Rome to an extent superior to all other churches is simply imagination.
Then you have the problem of the aberrations that result from making the church supreme over Scripture enables, such as defining "one Lord" to mean he was once a man, etc.
However, in a more restricted sense of OLOFOB, individual groups under both models for unity can claim to hold to "one Lord, one faith, one baptism." A basic unity under Scripture as the supreme infallible standard is seen among many groups by common affirmation and contention for "one Lord" as meaning the Trinity, and salvation by faith alone appropriating justification, but not alone as not resulting in works of faith. And which results in having One Father in all, by the One Spirit.
As for one baptism, the Scriptures mention more than one, and the one baptism is can be understood as the commanded ordinance which confesses faith in the Lord Jesus, while the baptism of the one Spirit into the one body of Christ which happens at conversion, (1 Cor. 12:13) and the baptism with the Spirit (Acts 8:14-17; 10:43-46;15:7-9) falls under "the doctrine of baptisms," plural, listed among fundamental beliefs in Heb. 6:2.
Again, you cannot escape interpretation of either Scripture or the church on the personal level, or by individual church groups.
And while the ecclesiastical magisterium is to hand down authoritative judgments, yet its authority is not based upon a claim to perpetual assured infallibility, but upon Scriptural substantiation in word and in power, which is what was behind that of Acts 15 .
And while ideally there should be a central magisterium, rather a divided kingdom with an individual magisteriums, which Rome is only one of, but she has more than manifested that she is not worthy of her elitist claims, based upon the Scriptural standard for authority, upon which the church began in dissent from those who also claimed more for themselves than what is written.
Finally, the only unity that Scripture affirms is that which is of the Spirit, (Eph. 4:3) which most essentially is that which true born again believers realize among themselves, which is greater than their differences (and comprehensive unity has never been realized), which is based upon a shared Lord, faith and baptism, that of a shared evangelical conversion to the One Lord, by the one efficacious faith that is behind it, and the one baptism that results from it.
Well, perhaps some case could be made for unity within ROME, but then there's the EO, Russian Orthodox, Ukrainian Catholic,....
http://en.wikipedia.org/wiki/List_of_Catholic_rites_and_churches
Last count, according to Catholic FReepers, is TWENTY-TWO different flavors of Catholicism.
Hardly *one faith*
I’m sorry for not replying sooner. Duty calls.
I think we are in agreement that sola scriptura fails in practice. This and the doctrine being not in scripture were the two points I had in this thread.
I appreciate your courteous discussion very much. Thank you and may God bless you and yours...