With regard to the validity of a marriage at the justice of the peace, Karl mentioned in a prior thread (see “Poll: How long have I been married?”) that the validity of the marriage depends on whether the participants are under the Church’s authority.
My question is when is someone under the Church’s authority? How does this apply to fallen away Catholics? What about a baptized Catholic who joins a non-Catholic church? Or a baptized Catholic who simply does not believe in Christ anymore? Can you quit the Church to be not under the Church’s athority and have your marriage be valid? Or is it once you’re baptized any marriage not according to the Church regulations is invalid?