Why is Kennedy killed sometime between early November 1960 and 20 January 1961? Is this the work of some anti-Catholic fanatic? Apart from perhaps nailing a couple of female stars/starlets, and being a rich guy in general, it's tough to recall that Kennedy had done anything that might have made him a target during this interlude of maybe 75 days.
Just for the sake of discussion, assume it is some sort of anti-Catholic total nut job (not sure how/where you'd find one in the US since there's no Orange Order to speak of* that might produce anyone that insanely fanatic, and the KKK by that time had essentially dropped its anti-Catholic line) since that seems to be the simplest assumption. Would that yield an oddly (for the US) pro-Vatican surge, wherein the Church actually sees a temporary halt--perhaps even a rise--in membership, even in the heart of the hard-core Bible Belt?
* Yes, the Orange Order does exist in the US, but you'll need a strong magnifying glass to find it. As best I can tell, there are no chapters in southern NJ, and the nearest is somewhere in northern DE. And you need to do some homework to find its existence at all.