The persons or churches that devote themselves to love and good works by encouraging one another to walk in the Holy Spirit, subdue the flesh, and seek first the kingdom of God.

My second answer:

I think the practice of the Orthodox, especially in the matter or icon veneration and overconfidence in their traditions, is a deal breaker. On their preservation of apostolic theology, though, I have learned a lot from them. The Roman Catholics have destroyed the faith of the apostles by ridiculous papal decrees and centuries of irreligious behavior by their pope and clergy. The Protestant Reformation was insufficient to restore the faith once for all delivered to the saints from the Catholics because sola Scriptura is neither scriptural nor practical.

No church so large as Protestant, Roman Catholic, or Orthodox has recovered from the introduction of the public–sons of Belial who walk by the spirit that works in the sons of disobedience–into the church and its affairs. Paul gives a long warning about this in 2 Cor. 6 and a short one in 1 Cor. 5.

Individual churches can and are rescuing themselves from the influence of proud & wicked men, but as long as education is honored above righteousness, it seems to me we are fighting a hopeless battle. As long as only the few are doing the exhorting (the super important parakaleo-ing, cf. 1 Thess. 5:12-14; Heb. 3:13; 10:24-25), the church is crippled.”

*Note: By definition, “Orthodox” and “Catholic” and “Protestant” are “denominations” because there name differentiates them from other Christian organizations. I was neither trying to make a religious nor polemic point by using the term.