How can you possibly argue with 1000 silverlings that all authority rest within the Church and then turn right around and argue with me that people can be saved outside of the Church? You can't have it both ways. Either the Apostles hand down everything INSIDE the Church or they didn't. Either the Church hold the truth or it doesn't.
I must warn you that I had a bad several days and I'm in a crabby mood.
I have been asking Silverlings to show me where the Old Testamant gives the Apostles authority to nullify the command of Circumcision - which would eliminate Sola Scriptura. But that aside, to your question. Recall that God writes His Law on EVERYONE'S heart. He also ORDINARILY chooses to draw people to Himself from within the visible Church. However, God is not bound to the visible Church's sacramental system - as Augustine argued vs. the Donatists. (sadly, he didn't make the connection regarding the absolute necessity of infant baptism). As a result, God calls people outside of His visible Church to become part of His Church, His people. The Church preaches a Gospel of Love, His one commandment. Those who love our executing this Law of Love given by our savior, for which by no other name comes salvation.
Even men such as St. Justin the Martyr (150 AD) saw in pagan philosophers a seed planted by the Logos - His abiding in them in an incomplete way as yet, a proto-Evangelium. Mysteriously, such men who follow the inclinations of the Logos, God's Wisdom, along with God's Spirit, Love, are united with the Body of Christ.
I have noted lately that I, too, am a bit frayed lately.
Regards