"post Conciliar laxity, modernism, and heresy" are in the eye of the beholder who is usually someone who is afraid of cultural progress. In my pre-Vatican2 youth having a protestant best friend was at best considered poor form since protestants were destined for Hell. My family and his took that "teaching" with a grain of salt since it was a throwback to an earlier less tolerant time which went out the window with Vatican2. That was a "teaching", not dogma so teachings do evolve even if you feel dogma does not. The church's stand on divorce/remarriage and full communion is likewise a teaching, not dogma,  which is why Pope Francis is well disposed to re-visit it, the opposition of the remaining dubia cardinals not withstanding.