I have been reading various Church documents and Papal statements on NFP and I’m trying to understand the difference between the terms Grave, Serious, and just in relation to reasons to practice NFP.
Some popes have stated their must be “serious” reasons for NFP, the catechism and the teaching of JPII mentions “just” reasons. I know that some people say there must be “grave” reasons, but I can’t find the word “grave” in any church document on the matter.
Does serious and grave have the same meaning in this context. If so, what is the exact definition of this in relation to this topic?