A civil liberties group has launched a campaign criticising the United States Air Force for showing "favoritism" towards Christianity.

The Military Religious Freedom Foundation (MRFF) has erected a billboard reading: "Welcome Mr. President to Our AF Academy. Why is Jesus Commander in Chief Here?" near the academy on I-25, Colorado Springs.

It plans to have a banner flown by a plane that says "Why is Jesus the Commander in Chief at USAFA?" when President Barack Obama speaks at the Air Force Academy's graduation on Thursday.

"At the Air Force Academy today, it's a freaking train wreck when it comes to the separation of church and state," Mikey Weinstein, founder of the Military Religious Freedom Foundation, told Denver7.

"We've had cadets bullied and pressured, members of the staff pressured to attend the national pray events that occur there," he said.

"This destroys unit cohesion, good order, morale and disciple."

The civil rights group hopes Obama will tackle what they see as a Christian bias, and ensure the Air Force complies with the consitutional separation of church and state.

"We want people to be judged on their value, talent, patriotism and their character, not whether they accept Jesus Christ as their personal lord and savior," Weinstein told BizPac Review.

"When it comes to separating church and state, the Air Force Academy shows overt favoritism to one version of Christianity."

The MRFF has previously attempted to stop Air Force football players from praying on the field before games, however in January it was ruled the players were protected by the constitution.

In a statement, the Air Force said that it puts "a high value on the rights of its members to observe the tenets of their respective religion or to observe no religion at all."