1. Currently, there is no set definition or level of atheism. I believe Dr. Whitley is suggesting the need to categorize the term into sub-groups.
This is a reasonable interpretation of the footnoted section of the abstract.
2. In the body of his text, Dr. Whitely explains that there are few studies dealing with atheism and mental health. He suggests further study.
The abstract states, "(2) there needs to be greater systematic investigation into the influence of atheism on psychiatry as an institution"; your explanation does not jive with it. Given your access to the article, you should quote relevant parts from the report itself.
3. Dr. Whitley examines atheistic leader from four countries who brutalized and killed it's own citizens. He is suggesting that further study in relation to atheism/mental health needs to be explored.
The abstract states, "(3) the relation of atheism to mental health needs to be explored by examining atheistic theory and its practical application, especially as it relates to the human condition, suffering, and concepts of personhood", therefore again, your explanation does not jive with it. Again, given your access to the article, you should quote relevant parts from the report itself.
In short, holybuckets, we're going to need more than just you saying, "hey, this article says that atheism might be a mental illness", especially when you're basing that off of things that aren't stated in the abstract and frankly, don't follow from what is stated there.