How and why did American Indians both adapt some aspects of European culture and resist European attempts to change their values and beliefs?

Many of them assimilated and learned the language and started behaving like Europeans because they believed that it was the best thing to do, many even adopted Christianity. On the other hand, they didn't want to lose their identity so they fought. They wanted to live freely according to their laws and didn't want to have their land taken away and for European laws to be imposed upon them. They adopted systems like trading and using money but they tried to stick to their roots.