America become a great nation because it had immense natural resources and by the time of independence the native population had been severely reduced by plagues of diseases that they had developed no resistance to. The conquest of the native population was not carried out due to "Christian values".
Where the natives had been converted to Christianity, they were normally driven off the land by greedy well armed settlers, and where natives resisted conversion, the same thing happened. The largest populations of native people are the Navajo, the Cherokee, the Chippewa/ Ojibway and the Sioux (Lakota). Christianity is not a major thing with most Native Americans, and the mission schools in both the US and Canada are widely despised for their singularly cruel and culturally destructive treatment of native children for about 100 years.