It certainly must have this wider, singular sense: because the Church is the Bride of Christ, and I don't think He means He has a harem.
You got it right by capitalizing Rock. The Rock the church is built on is Christ, the Rock of our salvation. The Church is likely to be much bigger than a local congregation, but that does not change what Paul wrote to the Colossians. He did not say "sit on your hand until I get there to tell you what to do", he said "what's the matter with you that you lack to faith to judge these matters for yourselves". Maybe I missed it, but it sure looks to me in that passage that he NEVER told them what to do, he had confidence that the Holy Spirit would guide their judgment, didn't he?
Deu 32:4 "The Rock! His work is perfect, For all His ways are just; A God of faithfulness and without injustice, Righteous and upright is He.
Peter and the Apostles were hardly perfect.
Mat 16:23 But He turned and said to Peter, "Get behind Me, Satan! You are a stumbling block to Me; for you are not setting your mind on God's interests, but man's."
It certainly must have this wider, singular sense: because the Church is the Bride of Christ, and I don't think He means He has a harem.
Indeed, the Church of God is the Bride of Christ. She is very easy to identify, too.
2Co 11:2 For I am jealous for you with a godly jealousy; for I betrothed you to one husband, so that to Christ I might present you as a pure virgin.
Rev 12:17 So the dragon was enraged with the woman, and went off to make war with the rest of her children, who keep the commandments of God and hold to the testimony of Jesus.