It wasn't about God at all or politics. It was about MONEY and LAND.
Those institutions wanted and GOT the oodles of land that the Catholic Church owned. It was all about GREED.
No, it wasn’t all greed, or at least not simple Henry VIII type greed. This sort of thing went on long after both the English and French states had sequestered the bulk of Church lands and given them away to their favorites.
It certainly was politics, to a degree, but even that was marginal. There was no political basis for British intellectuals and politicians to be anti-Catholic to the degree so many of them were, as the remnant English Catholics weren’t even a plausible threat to the established order after @1750. A great deal was ideology, and religion, all this being inextricable.
In continental Europe in large part it was clearly politics., as there was a Catholic-Protestant split among the European powers and factions within them. Bismark for instance (a purely political animal like no other) objected to any institution he couldn’t control, and said so, quite frankly. He stopped persecuting the Church when he figured he needed them and could make deals.
Marx (and hordes of both his predecessors and followers) on the other hand had both an ideological and practical objection to Catholicism. Others like Victor Hugo had a purely ideological-philosophical cause.
Its complicated.