I am changing Mill's status from atheist to ambiguous. I think the person who created the article misunderstood the quote they were using: "Although Comte said he understood Mill's reasons for rejecting publication of the pamphlet, he still thought it would provide a good opportunity for the advancement of positivism. Comte welcomed the prospect of being attacked publicly for his irreligion, he said, as this would permit him to clarify the nonatheistic nature of his and Mill's “atheism"."
In this quote, it says that Comte is eager to clarify that his and Mill's "atheism" (the fact it's in quotes is important) is nonatheistic.