Are you church of Christ? Are you defending the CoC. Or do you belong to a group that also thinks they are the one true church?
I would defend the C of C. We are PART of Christ’s church, which by scriptural definition, is THE ONE TRUE CHURCH. I do not join my brethren in World Bible School saying that ONLY members of the Restoration movement, specifically those calling themselves the Church of Christ, will be going to heaven. God knows his children. I will not judge another man’s servant (Romans 14).
To your question as I understand you’re using the terms, I don’t believe any denomination of the Catholic is “the one true church”, nor do I believe all of them are, or even a few of them are. I believe God’s word plainly describes who are His ‘church” (gr. ekklesia, common Greek word for assembly of people). Whether one is part of His people, and worshiping with others of His people locally as described and commanded in His scriptures, depends entirely whether that person is following what is clearly written.