A small booklet, Did Charles Darwin Become a Christian? by Rusch and Klotz, calls for caution when considering these widely circulated pamphlets. Rusch, in particular, casts serious doubt on the truth of the alleged conversation between Darwin and Lady Hope. He finds several aspects of the account either contradictory or suspiciously untraceable.
The Rusch/Klotz document might not be described as gripping or exciting reading, but if you have been circulating the questioned pamphlets you should do your homework and investigate closely the claims entailed.
Rusch perhaps depends too much on logical deduction (humans are not really that logical!). It is conceivable that Darwin could have been exploring the Bible and Christian worship more closely without necessarily feeling bold enough to discuss this at length in his correspondence with other scientists.
So, did Darwin become a Christian? We don’t know—it’s between him and God. We just have to be careful to get our bit right.