As far as I know sanguines don't fully leave their faith, though it is very easy for them break it's commandments on and on! While a melancholic is not tempted by worldly allures, he might lose his faith completely by reading dark novels of nihilists!
That's how I spent my twenties. I wish I was joking!
I was in such bad shape that the Protestant philosopher Kierkegaard actually helped put me on the right track with his Concluding Unscientific Postscript -- to his credit, despite not being Catholic, he saw the anti-Christ and meaningless messages being peddled by the likes of Hegel. In that book, at the end, he talks about giving all credit for everything you do to God, which may have been hypocritical in his case, who knows, but it got me thinking, the light began to go on. He sort of cut through the intellectual fog I was in. So may God have mercy on his soul, I hope he was in invincible ignorance though it's unlikely.
I guess you will have to rethink what you said about me being a choleric, spouse. I am proof that melancholics can change; they can become massive cholerics, and then maybe even sanguines!
But you misread what I said, this author is not at all positive about melancholics, he considers them to be more troubled than cholerics or sanguines, probably because those two are a little more active in personality.
I'll post the chapter, Roman Catholic, I have 40 pages left in this chapter on the temperaments. Father Gabriel is compiling all this, he said he was going to send it out to people. The unofficial deadline, which I intend to meet anyway, is May.