The funny part is they use this so-called argument in favor against God or religion and used in a negative way when in fact it supports it, that's the irony of it all. God is universal and each culture has their own interpretation of that Reality, with only a few interpreting an atheistic view (which is fine too). Just like when you go to different countries and they all have their own way and style of cooking, or their own style of clothing, or their own style of buildings, architecture, language, education and of course religious ideas and concepts about the Creator.
Do we ever say that those things don't exist because they all are different one from the other? or that they are not legitimate? or they have no value? Of course not, so why when different cultures express their religious beliefs in different ways is it suddenly a negative or something used to disprove God? that's stupid, of course every culture will have their own way of expressing the SAME Reality, how could they not? God is one massive phenomenon, and there are many aspects of God and MANY places in creation even beyond this one universe, we're talking about an Eternal Reality with no limits and no boundaries. No one can put restrictions and limitations on that.
There's also deeper reasons for this phenomenon besides just different interpretations, when you leave this world there's not just two places or one that an individual can go. The afterlife and the parallel worlds are just like our universe, there's many planets, galaxies and places, cultures, groups, heavens, hells, peoples, creatures ect ect so there are accuracies involved in different expressions of God and creation because there are countless cultures and places outside the physical universe. And that's the fun part, most people are stuck in one culture and belief system not knowing God is a God of variety and flavors.
God enjoys creating countless souls and in doing so God knows there needs to be countless places for the soul to exist. God knows that not all cultures will be the same and reflect the same things that is obvious and God accommodates every group of people. That doesn't mean that everyone goes to a heaven when they leave here, cause and effect and Karma are still real factors no matter what culture you were raised in. But each culture of souls have an extended culture that exists beyond this one, this is why for example you have a group like the Native Americans always putting emphasis on their culture and their ancestors because they know that there will be an extension of their culture when they die and leave this world.....why Christianity always puts emphasis on the Christian Heaven or Hell, they know there will be such a Kingdom that exists and this is the same for each culture and religion.
This does not imply that souls can't mix and match either, the soul is free to choose what it wants and what it relates most with. Their main obligation is to follow the universal rules of creation. And that they answer to the call of spirituality (no matter the belief system), be willing to progress in creation.
Each religion and culture believes their ideas are most accurate, that they are special among the others and that is okay too, just like Americans love America and believe their country is most desirable....they call that patriotism. The same thing applies to religion and their cultures, that's what makes them special and unique, they call this a creed. So really it is irrelevant to bring up the fact each belief system claims they are the only one that's legit (if they even do). That's the nature of all this, and why people have such passion in their beliefs and that is the point of creeds and zeal, it anchors the individual to their culture and way of thinking. It creates a passionate binding for each culture. If you understand it according to the terms I just laid out everyone should be quite happy, and delighted and overjoyed knowing that God is that friggin cool. It's a refreshing way of understanding God and I'm not just blowing smoke up people's arse this is true about creation. It also should answer and satisfy many questions people have about God and religion.