Everyone speaks of Lincoln's faith and in a way they're right. In his later life, most of his speeches were infused with reference to a vague 'higher power' or 'great creator', but he certainly wasn't religious in the traditional sense, especially for the times.
He best summed up his own views when he said "When I do good, I feel good. When I do bad, I feel bad. That is my religion."
Like Jefferson, Lincoln most likely thought of Jesus as the greatest philosopher but avoided what he called religious enthusiasm.
He was raised in a very religious Baptist household, but never officially joined any church. This was at a time when church was the main social activity and surely must have raised eyebrows.
Lincoln did get involved in the temperance movement which was mainly backed by protestant churches but was turned off by their focus on looking down on the sinners. Lincoln wanted the movement to focus on making positive changes in the lives of individuals that have trouble with alcohol and eventually lost faith in it.
Lincoln mocked the idea of religion when he was younger saying things like:
"When I see a man preach, I like him to look like he's trying to avoid bees."
He resented hypocrites that had a holier than though attitude:
"My experience is that someone who has no Vices also has no Virtues."
Certainly Lincoln was not like Jefferson who had his own version of the bible where he blacked out all of the miracles of Jesus and ended the gospel when the rock was rolled over the tomb, but he would probably have a hard time getting elected today.
It's just hard to believe that a person who didn't attend any church could get elected to the highest office 150 years ago, but most likely not now when we've discovered things like the big bang, evolution, space travel etc.