No religious system can be founded otherwise than upon the nature of God and of men, and upon the relations they bear to each other. But, in order to judge of the reality of these relations, we must have some idea of the Divine nature.
But everybody tells us that the essence of God is incomprehensible to man; at the same time they do not hesitate to assign attributes to this incomprehensible God, and assure us that man can not dispense with a knowledge of this God so impossible to conceive of. The most important thing for men is that which is the most impossible for them to comprehend. If God is incomprehensible to man, it would seem rational never to think of Him at all; but religion concludes that man is criminal if he ceases for a moment to revere Him.
I’ve done a bit of digging around about the typical education of an abbe of Meslier’s period. So far, I don’t really know – but there have been several bits by Meslier that sound like they are strongly influenced by ancient skepticism such as that of Sextus Empiricus or the philosophy of Epicurus. I doubt the religious schooling of a 16th-century catholic would include those, but his being literate would imply he could read Latin at a minimum, which would set him up for Lucretius, Diogenes Laertius, and Sextus. I can imagine a believer who decided to learn a bit of philosophy, who stumbled onto Epicurus (via Lucretius) and suddenly his faith was taking on water.
A blessed and indestructible being has no trouble himself and brings no trouble upon any other being; so he is free from anger and partiality, for all such things imply weakness. – Epicurus principle doctrine #1
That is the root of Meslier’s comment #5: a supreme being would be as imperturbable as Epicurus says. The god of the christians is this great emotionally needy nebbish-god that is inappropriately concerned with being worshipped. And, worse, the worshippers of that god are full of assertions about what god wants and needs, and god remains inexplicably silent.
Well, not inexplicably. There’s one simple explanation.