Pope Francis is in Washington, D.C. today where he’s received a rock star’s welcome. The trip is his first visit to the U.S. where President Obama welcomed him along with thousands of the faithful.

But, some say he’s about to make a huge mistake.

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While in Washington, the pontiff is expected to canonize 18th century missionary, Father Junipero Serra. Serra, a Franciscan friar from Spain, is credited with bringing Christianity to the land that would eventually become California three centuries ago. The indigenous people of that territory say Serra was brutal to Native Americans. They accuse him of believing Europeans were superior to the native people and creating a militarized mission system that spread disease and caused thousands of deaths.

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Some critics believe Serra's canonization has been fast-tracked, even though only one miracle has been credited to him, because the current pope is also of Latin descent.

"It is very offensive to canonize the person who actually enslaved, whipped, tortured and separated families and destroyed our cultural and spiritual beliefs," Amah Mutsun Tribal Band chairman Valentin Lopez told NBC News.

The canonization Mass at the Basilica of the National Shrine of the Immaculate Conception is scheduled for Wednesday afternoon.