This law is unlikely to create problems for Indians who are willing to hew to the Christian line, but Texas is home to lots of Indians who follow the Native American Church. It appears to me from the outside that NAC people are as Christian as Mormons are, but I doubt that most Christians in a position to place children for adoption would see it that way, or know the difference between peyote and heroin.
Then there are always some Indians still doing their best to follow traditional beliefs. (Where we say “traditional,” many Christians who demanded this bill would say “heathen.”) Other Indians let go of their traditional beliefs but still did not buy what the missionaries were selling. They end up like a lot of white people: not atheists or even agnostics but rather “unchurched.”
Source: Christians Only: The New Anti-Native Adoption Law in Texas - Indian Country Media Network