Oddly enough, compared to the rest of the shows on TV today, IMO, the Simpsons is actually one of the more family-friendly shows. When the Simpsons first aired, it was considered raunchy - today, it’s considered pretty tame. That has nothing to do with the show itself (though it has changed the focus from Bart the brat son to Homer the bumbling, though loving, father). It has everything to do with how programming has changed in the 23-24 years that the show has been on the air. During the run of the Simpsons, the programming around it has changed from “The Cosby Show” to “Seinfeld” to “Two and a Half Men”.
The Simpsons does poke fun of religion, primarily Evangelical Christianity (though it seems to be in a light-hearted way - the way friends sometimes trade verbal jabs with each other), but it doesn’t promote homosexuality, fornication, drug use, or even profanity, like many other sitcoms do (including the other prime-time animated sitcoms). In addition, it’s not full of the violence seen on the multitude of police procedurals. Of course the program isn’t perfect - but it’s a lot better than the alternatives.