Do you believe that God is sovereign?
Do you believe that He would allow apostates and unbelievers to take control of His church, the very church which He promised immunity to the Gate of Hell?
If you do, why aren't you a Mormon?
His church is the body of believers everywhere, no matter what the denomination. There are no apostates in the true church, even though there could be plenty in the Catholic church.
The gates of hell will not prevail against God's church not because it's the Roman one but because it's comprised of the body of believers everywhere for all time regardless of religious affiliation.
Nor did God promise immunity from apostates creeping into local congregations meeting together. We've been warned of that very often in Scripture.
No church on earth is perfect. All churches are judged according to how closely they adhere to the word of God.
Rome shows itself to be outside the orthodox teaching of Christ and the apostles by its glorification of fallible men, empty relics, blasphemous rituals, a simple woman and men's own good works.
There is no "alter Christus:" no "other mediator;" no alchemy of the mass; no "queen of heaven;" no purgatory; no limbo; no infallible old men; no sacrament of reconciliation; no confessions made to other men for forgiveness of sins; and no hierarchical priesthood which excludes all believers.
Read the Bible. Christ has risen. His sacrifice is complete. His sheep have been forgiven. All the rest is gratitude and glorifying His name ALONE.
Happy New Year, everyone! Our Lord, God and Savior reigns.