> This does not apply to monotheistic faiths. The first problem is that they claim that their god is the only god. The second problem is that they prescribe punishments (death, eternal hellfire etc) for those who do not accept their god.

You've completely misconstrued the nature of tolerance.

First, the only valid reason to hold to any religious faith is that you are convinced that it is true. Period. This isn't a narrative among many that you can pretend to believe because it adds structure to your life or some other benefit. You believe it primarily because you think it's true. (The benefits are secondary, though you would expect them if you've got truth. Truth allows you to live in conformity with reality and your own nature and thus your own good.)

Second, you have completely misconstrued what Abrahamic religions believe w.r.t. God. God is not comparable to pagan gods. Pagan gods are just more powerful beings. Each pagan god is just one being among many. That is not the case for the Abrahamic religions, certainly not Christianity and definitive not Catholic understanding. God is the Ipsum Esse Subsistens or subsisting Being Itself. Jesus is the Logos, not some guy competing for marketshare with other gods. This sort of monotheism isn't the reduction of the pantheon to one god. It is the definitive abolishment of the superstition of pagan religion. You actually don't need to appeal to any of these religious faiths to arrive at God thus understood. All you need is metaphysics.

Third, the claim that a lack of faith in God is sure to lead you to hell has nothing to do with intolerance. That's like saying that anyone who claims that driving off a cliff will kill you or taking drugs will destroy your life is an intolerant person engaging in fearmongering to control people and keep them from having fun. If you were headed toward a cliff, or about to shoot up some heroin, wouldn't you want someone to tell you that you'd about to ruin your life or kill yourself? If someone believes that a lack of faith will lead to your eternal damnation, then it is rather a sign of charity and love that they should let you know you're in danger, even if they're wrong. You can appreciate the concern at the least. You seem to be suggesting the absurd idea that it is intolerant to be certain of your beliefs and thus certain that someone else is in error. That's preposterous. What's intolerant is this definition that requires people to artificially deny their certainties and "tone it down" because their beliefs make some people feel uncomfortable for some weird reason. Mind you, believing a lack of faith is a path to hell does not imply forcing people to accept that faith. The Catholic and Christian tradition recognizes the need to evangelize, but not the legitimacy of coercion. Coercion doesn't even make sense since free assent is necessary for faith to be authentic anyway. All you'd get are people pretending to believe to avoid unwelcome consequences, and that's pointless and would constitute fraud at best (for which they might not be culpable if the coercion were severe enough). And FWIW Catholic tradition as far as I know is more or less consistent in at least suspecting that most CATHOLICS probably end up in hell.