When the Nation was founded, 85% of it's citizens were Christian of some denomination. So, it was understood that Christianity would be common and the protections were against one single denomination ruling the others, like the English Anglican church. Nobody tolerated Islam and we fought the Barbary pirates very early on. We were definitely founded as a "Christian" nation and thank God for it! We never would have survived this long with out Christians - whether you are one, support one or even just tolerate them, you owe them a huge "thank you".