Whilst it's hard to argue that Christianity isn't more deeply ingrained into at least American culture, I'd argue that this serves more so as a disadvantage against it rather than an advantage. Think of it as a guest in your home, it'd be improper to keep amenities for yourself whilst keeping them from your guest, we are more comfortable with a member of our family than this guest so in many cases things are given to the guest that aren't provided to the family member. Americans are much more comfortable with Christianity as it has a deeper history with America (an incredibly high majority of citizens and elected officials were and are Christian) compared to other religions, that still are technically "outsiders" when compared to Christianity. This discomfort leads to other religions being treated with more kindness and respect in fear of offending followers. Please don't confuse "comfort" for "favor", that's not the case as it was with the previous, admittedly flawed analogy for this comfort causes it to take an authoritative position, which is not in favor today. It serves as a power to rebel against, humans naturally favor the under dog and so religions such as Islam and Judaism (it's a bit late but I am more so focusing on Abrahamic religions as they are the religions most in the limelight in America) are viewed as being more sympathetic. For proof of this favoritism see the constant (though sometimes well deserved) critique of Christianity compared to the hesitation of connecting terrorist acts that have been connected to ISIS to Islam, in fear of offending all Muslims, including the non-violent ones. But no one cares for the moderate Christians.
Christianity, and to a lesser extent, the other Judeo-Christian religions, get preferential treatment over every other religion in the United States. Christmas, a Christian holiday celebrating the birth of Jesus of Nazareth, is a federal holiday. No other religion has a holiday that is recognized as a federal holiday. Our paper money says "In God we trust" on it, which is a reference to the Judeo-Christian god.
Certain religious faiths definitely receive special treatment. It is my belief that there is a great deal of lingering resentment felt by members of certain religions as a result of hardships that they faces in the past. This bitterness leads them to seek out preferential treatment and sympathy from the rest of the population. Many of these believers seek out an added level of sensitivity from the rest of the world when it comes to topics related to their faith. One example of this is how members of certain Native American Tribes petitioned for the removal of tribal themed headdresses from all Redskins football games.
America is founded on the separation of church and state. Because of this, I disagree with the assertion that certain faiths are treated more fairly than others. Our country is open and welcoming to all, and works to create a safe space where all may worship peacefully without preferential treatment.