They see it as their Christian duty. But others disagree, saying it extends the hand of fellowship where it was never intended to go.

Two Protestant churches are taking some heat from critics for opening their church buildings to Muslims needing places to worship because their own facilities were either too small, or under construction.

Heartsong Church in Cordova, Tenn., let members of the Memphis Islamic Center hold Ramadan prayers there last September. And Aldersgate United Methodist Church in Alexandria, Va., allows the Islamic Circle of North America to hold regular Friday prayers in their building while their new mosque is being built.

Diane Bechtol of Aldersgate says this is something Christians are called to do: Be neighborly and develop relationships - even those who don't share your beliefs.

But Dr. Alex McFarland, a Christian theologian and radio talk show host, charged these churches “have crossed the line from respect and tolerance, to ... affirmation and endorsement.  "We as the church are called to show love, we're called to help. But to let a building simultaneously be used for the activities of a mosque and also the activities of Jesus Christ, it's just incompatible. And I think it's one more example of political correctness and hyper-tolerance gone awry."

Elsanousi is National Community Outreach Director of the Islamic Society of North America. He says "allowing people the freedom of worship is respectful and strengthens the relationship."

That trend may continue as the Muslim population across the U.S. continues to grow. Mosque construction is at an all-time high. As of September, there were 1,897 mosques in the United States, a 57 percent increase since 2000.

McFarland says the groups run the risk of creating something called “Chrislam” - a combination of the two faiths that essentially ignores the big white elephant in the room: the exclusive claims of both Christianity and Islam.