Was Abraham Lincoln a Christian?

Since he grew up in a deeply religious Baptist family, most people think it goes without saying that Abraham Lincoln was a Christian. After all, he's thought of today as the best President the US ever had.

One look at him gives the impression he's not only off to Church but wouldn't be out of place up there pounding the pulpit to the congregation. After all, this is the compassionate President who abolished slavery.

It comes as such a surprise, therefore, to people who hear he was not that it's being pointed to as a Mandela Effect. He never even became a church member.

Civil War

He was the 16th US President and is widely regarded as the model of decency all US citizens should emulate. Born into poverty in a log cabin in 1809, his mother died when he was 9. He was self-educated and became a lawyer. He was a keen reader from an early age, and studied the Bible extensively.  Originally a member of the Whig Party, he became a founding member of the new republican Party in 1849. He served in the Illinois Militia as a captain fighting in the Black Hawk War

Lincoln was responsible for healing the US after it's bloody civil war, however one aspect which isn't mentioned much is that both sides actually had different ideas about the Bible. He was even called an infidel at the time by various devout religious groups for not subscribing totally to their particular variant. The only other non-Christian president was Thomas Jefferson

People assume he must have been a Christian mainly because his appearance is that of a stereotypical devout preacher, and are aware that at the time of his political activity, most around him were so there's no obvious reason to think otherwise.