How do you know what the Lord is saying through the Bible when three Spirit-filled pastors disagree on the interpretation of a Biblical text? The Church is "the pillar and bulwark of truth" (1 Tm 3:15).
How do you know if Jesus is really present in the Eucharist? (Very good Christians honestly disagree on such an extremely important matter.) The Church is "the pillar and bulwark of truth" (1 Tm 3:15).
Many denominations maintain that morality, especially sexual morality, needs to be updated and applied to our modern times. Yet isn't the truth always the truth? Isn't there right and wrong? Isn't there objective morality? Shouldn't society submit to divine revelation and not vice versa? We need the Church, "the pillar and bulwark of truth" (1 Tm 3:15).
Without the Church, clearly defined and in continuity with the Church founded by Jesus, we don't know what books are in the Bible, how to interpret important parts of it, and how to apply it in our world today. Without the Church, we don't have a Bible, accessibility to the whole truth, or protection from being brainwashed by secular humanism. "I am writing you about these matters so that...you will know what kind of conduct befits a member of God's household, the Church of the living God, the pillar and bulwark of truth" (1 Tm 3:14-15).