sure, but that was typically necessary for developing a modern capitalistic economy
hence why thr soviet union had to undergo a similar process and cruelty, with possibly more casualties due to bureaucratic incompetence
marxism itself viewed this as necessary and positive, so marx hand-wringing about it isn't meaningful.
patriotism and religion often thrive among the poor and peasantry, tho
because they are unintelligent savages
marx was atheistic because he came from a wealthy family, and he was not seriously working-class
promoting atheism to the low-class masses is foolish, because their atheism will not be intellectual in nature like marx's, it will only be a form of license for hedonism and licentiousness. that is what we see in modern democratic society
marxism claims to be a materialistic ideology formed from class struggle, but it's the intellectual product of two upper-class men who were well-read in hegel and passionate about german philosophical debates. it should be taken as a curiosity of german philosophy, not a political program of social change which it has no worth for
but most of marx's ideas were formed in the process of adolescent rebellion against his father and other father-figures like hegel, and expecting the result to be an operational model for revolutionizing society is foolish
But poor workers end up putting their hopes in those ideals because they are desperate, because they need a small halo of light in the darkness of their lives, that does not mean that they can start thinking seriously and deeply about theology or the development of national culture, as you said, they are not intellectuals with the time to delve into these things, they only cling to those ideals superficially like a burning nail so as not to end up killing themselves.
In any case, Marx lived before the Russian Revolution, he probably did not know that to form a modern industrial society capable of competing against capitalist societies it was necessary to go through a process of exploitation of the working classes.
This happened when Lenin took power in Russia and realized that going from an agrarian society to a socialist-industrial one in a single leap was impossible, that he had to go through a process of "passing capitalism" until the conditions were met for the socialization of the means of production.
Either he didn't think about it or he didn't give it importance, he lived in an earlier time.
I agree that promoting atheism among the normie masses is a bad idea, it only leads to cultural decomposition.
I also don't underestimate Marx for being an intellectual without a job... his ideology ended up creating gigantic revolutionary movements, and I love revolutions (personal take here), I can't do anything other than appreciate what he did. I understand that it was the manipulative Jewish Mass that won in Russia in the end, but it's not like I'm going to be empathetic to the tsars either.
The fact of being aware that Marx pointed out the Jewish problem makes me able to appreciate it, instead of dismissing him as just another conspiratorial Jew, as is done from the third position.