I should also point out -- there is no FASTER path to apostasy and loss of faith, OR spiritual blindness, than IMPURITY. I'm talking about sins against the Sixth and Ninth.
Impurity leads to worse depravity, going ever deeper into sin. No other type of sin has as many chains, or is harder to extricate oneself from, as the sin of impurity. And no other sin SO BLINDS its victim, as impurity.
I could give countless examples. My own cousin, who grew up attending the same Trad chapel, learning Catechism from Thomas A. Nelson himself, served Mass with me countless times -- he apostatized. I later learned from his MySpace page that he had lost his purity at 16. He never told me, though we were decently close friends as well as cousins. But eventually (especially after learning his fall into impurity) it made sense. He even said to the world that his main reason for leaving was "Catholicism was just too hard". Everything else was window dressing, cope, etc. He tried repeated blasphemy to deaden his conscience, but I also saw him rejecting (quite forcefully) the suggestion of some to become Protestant. Apparently the Catechism was too deep in his bones; he still knew Protestantism was silly and could never accept it. So, he became a statistic, and went from Catholic to "nothing". As an aside, he also believed in Theistic evolution.
And then the book "The Sinners Return to God", the chapter on impurity. There was a man who was willing to give up ALL HIS OTHER SINS, he had a priest at his deathbed entreating him to give up all his sins INCLUDING HIS CONCUBINE but in his final moments on earth, with his last breath, he embraced his concubine and died in a state of mortal sin. Horrible! That story stuck with me.
Last but greatest, Our Lady herself said that "more sins go to hell from sins of the flesh than any other". I believe it.