Translation:Muslims go to the mosque five times every day.
Wow, it is difficult question. I suppose you could say, "The muslims pray five times a day.", but it is more idiomatic to say "Muslims pray five times a day." The difference is familiarity or formality. "The muslims" is much more formal, as if "the muslims" were some obscure people you are just reading about in a museum or journal article.
I'm not sure what you are trying to say. To me, an accurate translation of המוסלמים is "the Muslims" and an accurate translation of מוסלמים would be "Muslims". Both make sense and mean basically the same thing and neither is more idiomatic than the other, at least in English.