At this current place and time, I am inclined to agree.
America is a Christian country with a Christian heritage.
We do have a Christian heritage, but we're not a Christian nation per se. Ours is not a theocracy, nor does it have an official religion. The government of the United States does not promote or prohibit any legitimate faith. This is all part & parcel with the First Amendment. (And before anyone asks, no, I do NOT agree with the ACLU's idiocy in having all religious references banned from all public places. We have freedom OF religion; not freedom FROM religion.)
I don't see Saudi Arabia issuing Christian stamps. In fact, Christianity is illegal in Saudi Arabia.
That is a large gripe, and certainly one I share.