Question if two baptized non-Catholics (let's say both are Presbyterian and neither has ever been married naturally or sacramentally) get married in a civil ceremony. Would they be living in sin or would it be a valid natural marriage?
Answer As far as I know, whatever marriages as are tolerated and recognized by the Church among those who are baptized but not in unity with the Church (assuming they have not personally left the Church but were merely raised in some non-Catholic sect and have not thought to question it) is that their marriages are taken as valid, at least from a contractual standpoint, and therefore licit and not fornication (assuming the partners were validly free to marry and give appropriate consent).
I focus on the "why" and "how" questions of the Faith and one`s need for the Church to overcome sin, live the life God wishes us, and to become what God wants us to be. I seek to provide insight and information such that you are then able to see for yourself the answer to your questions.
Years of extensive research, thought, and prayerful meditation on many of the issues that trouble Catholics today, taught catechetical classes to teenagers and adults, answered many questions already.