At no point did he claim that God had to intervene mystically magically miraculously or spiritually in order for wrinkled pods and smooth pod pea crosses to reproduce 3/4th’s smooth pods and 1/4th wrinkled pods. He proposed that it was something physical within the pea that was being held hidden in the first cross that came out in 1/4th of the offspring in the second generation.
And we now know what it was that was physically within the pea waiting to be expressed in subsequent generations - DNA.
If the evolution you accept has no physical cause then it is as useless as the rest of creationism and can lead nowhere and to nothing - exactly where you left it and seem content to leave it - unproductive and useless.
Of course not! Mendel was a scientist as well as a theologian. He was looking for God's laws, not God himself. Perhaps he would acknowledge that the only "mystical intervention" that God ever did was "in the Beginning" — and He's been pretty much keeping "hands-off" ever since (except for occasional and comparatively rare direct interventions — which we call "miracles" because we don't know what else to call them.)
To repeat myself: Mendel was not only a Christian cleric; he was a full-blown scientist.
Unlike in our present age, Mendel probably never ever thought that there was some deep, irreconcilable, mutually-exclusive divide between theology and science. That is a post-modernist, "progressivist" notion that in all likelihood he had not heard of, and which likely would have been unimaginable to him.
As a life-long student of human history and culture, may I observe that never before our own times did human beings believe in this so-called "Cartesian split" in the human knowledge domain. Descartes himself would probably have been appalled by this so-called "split." After all, he himself said that the idea of God is the most fundamental idea a man can have, on which is based every other possible idea a man can have, including the idea of his own conscious self.
The fact of the matter is: philosophy (and theology as the "queen of metaphysics") and science have been intimately engaged with each other for some 7 millennia at least. They have cross-pollinated ideas since Day One.
I cite as evidence the profound influence of Newtonian mechanics in the shaping of the philosophical ideas of such notables as Descartes, Leibniz, Kant, Hegel, et al.
To disparage philosophy is to express the preference for walking around on only one leg....
A person can always choose to do that, I'm sure. But why? It is ever so much more difficult to walk on one leg, when two are available to make our progress less difficult and more convenient....
So, why choose to walk on only one leg?
Well, where did DNA come from? That is, on what causal principle does it itself rest?
DNA is not "just" a physical molecule. It is one of the greatest "mysteries" in the world; for it not only maps the genome; but it can read it, and knows the "rules" of how to transcribe this intangible information into tangible physical processes/effects.
There is nothing in physics or chemistry that can explain any of this. Certainly Darwin is no help at all here — he never even heard of DNA during his lifetime....