Religion of the Presidents

This appears to be a fairly accurate visual about the religion of the Presidents of the United States:
Religious Affiliations of the Presidents of the United States

However, there might be some issues with how they chose to list them. For example, Rutherford Hayes and Barack Obama are listed as "Protestant, but not affiliated with any particular denomination." However, Hayes' and Obama's affiliations were different. Though Hayes attended church, prayed, and studied the Bible, he never joined any church. Obama, on the other hand, joined and was baptized in the United Church of Christ. Perhaps after he left Trinity UCC in Chicago, he may have remained unaffiliated. All that to say, sometimes there are more details that just putting a President under a heading. Hayes, it seems, could have as easily been listed as "no formal affiliation" like Lincoln.