It is still being debated
What religion was George Washington?
President George Washington was an Episcopalian
He was a member of the Episcopal Church, the American province of the Anglican Communion, which is a branch of Christianity, and which is usually classified as Protestant.
Washington and the family he was raised in were originally Anglicans. The Episcopal Church was not officially founded as a separate province within Anglicanism until 1789, after the American colonies proclaimed independence from Great Britain. Prior to the American Revolutionary War, the Episcopal Church was part of the Church of England, so Washington was originally a member of the Church of England.
While he was President, Washington attended Christ Church (an Anglican/Episcopalian congregation) in Philadelphia.
George Washington has frequently been described as a "Deist." Washington is not known to have described himself using this word, nor is he known to have been been a member of any Deist organizations. Some writings by George Washington indicate Deist beliefs; other writings indicate non-Deist beliefs.
Although he was an Anglican and an Episcopalian, Washington reportedly did not take communion and was not considered an official "communicant" (full-fledged adult church member).
It is generally agreed upon that Washington's beliefs could be described as "deist" during at least part of his life. Deism for Washington, as with most historical figueres classifed as deists, was never an actual religious affiliation, but was a classification of theological belief. As nearly all major political figures from Washington's era can be described as "deists" if a sufficiently broad definition is used an if the correct quotations are selected, classifying Washington as a Deist may not by particularly useful or distinctive.
Although the Episcopal Church is the only denomination Washington ever attended with any regularlity, he was not particularly dedicated to the denomination nor did he have a strong Anglican or Episcopalian self-identity. During Washington's era there was no real notion that he was a "non-Christian," and his denominational affiliation certainly placed him well within "mainstream" Christianity at the time. But Washington's religious beliefs could be classified as relatively broad and non-specific. His disinterest or disbelief in some mainstream Protestant Christian beliefs have led later (usually partisan) commentators to label Washington as "non-Christian."