1. There are probably billions of Christians who believe in evolution, and there are some Atheists who don't believe in evolution. Belief in evolution and Atheism aren't mutually inclusive.*
2. Darwin did know about the Bible, because he went to seminary and was on invited on his famous voyage partly as a chaplain.
3. That voyage was one of the most important sources of information, because he collected hundreds of fossils and live specimens. He also made extensive observations, writing extensive notes and making sketches.
4. Even after the voyage, he spent years more on research before publishing. He was so dedicated to getting the details right that he studied barnacles, of all things, for an entire decade.
5. As far as I know, Darwin never used the phrase "missing link" and the idea he recanted before he died is a PRATT that can't go away soon enough.
*The use of belief here is in the everyday use of the word. Unfortunately the word has connotations that make it problematic to use, but using other phrasing just strikes me as walking on eggshells to appease pedants who are acting in bad faith.