Matthew 28
18* g Then Jesus approached and said to them, “All power in heaven and on earth has been given to me. 19h Go, therefore,* and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the holy Spirit, 20i teaching them to observe all that I have commanded you.* And behold, I am with you always, until the end of the age.”
The Fathers do affirm the inherent danger in deliberately rejecting the Church. For example, St. Ignatius of Antioch wrote at the turn of the second century, “Be not deceived, my brethren; if anyone follows a maker of schism, he does not inherit the kingdom of God” (Letter to the Philadelphians 3:3). In the third century, St. Cyprian of Carthage wrote, “whoever is separated from the Church and is joined to an adulteress [a schismatic church] is separated from the promises of the Church, nor will he that forsakes the Church of Christ attain to the rewards of Christ. He is an alien, a worldling, and an enemy” (The Unity of the Catholic Church 6, 1). In the fourth century, St. Jerome wrote, “Heretics bring sentence upon themselves since they by their own choice withdraw from the Church, a withdrawal which, since they are aware of it, constitutes damnation” (Commentary on Titus 3:10-11).
Didn't see anything about being a part of the Roman Catholic church in that passage.
I do see a requirement to be a follower of Christ and all that entails.
The Fathers do affirm the inherent danger in deliberately rejecting the Church. For example, St. Ignatius of Antioch wrote at the turn of the second century, “Be not deceived, my brethren; if anyone follows a maker of schism, he does not inherit the kingdom of God” (Letter to the Philadelphians 3:3). In the third century, St. Cyprian of Carthage wrote, “whoever is separated from the Church and is joined to an adulteress [a schismatic church] is separated from the promises of the Church, nor will he that forsakes the Church of Christ attain to the rewards of Christ. He is an alien, a worldling, and an enemy” (The Unity of the Catholic Church 6, 1). In the fourth century, St. Jerome wrote, “Heretics bring sentence upon themselves since they by their own choice withdraw from the Church, a withdrawal which, since they are aware of it, constitutes damnation” (Commentary on Titus 3:10-11).
Let's put Titus 3 in a little more context shall we....you know context...some the rcc is not familiar with.
NASB Titus 3:4-10
Remind them to be subject to rulers, to authorities, to be obedient, to be ready for every good deed,
2to malign no one, to be peaceable, gentle, showing every consideration for all men.
3For we also once were foolish ourselves, disobedient, deceived, enslaved to various lusts and pleasures, spending our life in malice and envy, hateful, hating one another.
4But when the kindness of God our Savior and His love for mankind appeared,
5He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit,
6whom He poured out upon us richly through Jesus Christ our Savior,
7so that being justified by His grace we would be made heirs according to the hope of eternal life.
8This is a trustworthy statement; and concerning these things I want you to speak confidently, so that those who have believed God will be careful to engage in good deeds. These things are good and profitable for men.
9But avoid foolish controversies and genealogies and strife and disputes about the Law, for they are unprofitable and worthless.
10Reject a factious man after a first and second warning,
11knowing that such a man is perverted and is sinning, being self-condemned.
If you don't have faith in Christ you have separated yourself from Him. If you don't have faith in Christ you more than likely are not going to church. Though going to church doesn't make you a Christian. Only faith in Christ does.