I will set up some framework, set up my points and then answer my opponents.
1. Any setting of beneficial has to be about the world of the living, and not any afterlife. Since any claims of the afterlife aren't falsifiable, we can't have any meaningful or educational discussion about it. Pro seems to be discussing the real world, so I don't think this will be an issue.
2. Beneficial shall be defined as "resulting in good", as from Oxford Dictionary.
1. Only 34% of white evangelical Christians think homesexuality should be accepted by society. (1) I would argue that, while being Christian might result in a better situation for one's self, it doesn't result in good for society. The very fact that less than half of a group thinks that certain people should be accepted in society shows that they won't result in good for society.
2. Christianity pushes the idea of sexual purity and that only married, monogamous relationships are good. This leads to psychological damage to millions of teens who deal with an intense shame about their hormonal/natural sexual urges, as well as physical issues like body tension and trouble sleeping. (2) Anything that advocates for a specific rule of morality that inherently causes psychological damage can't be good for oneself.
3. The inherent idea of faith, which my opponent semi-defined as "just be confident in yourself without any backing" inherently leads to bad situations of abuse of power. Very simply, if people believe in Christianity without any backing, then this gives an opening of utilizing their faith to cause them to do different things. This can historically be seen as God being a justification for slavery, the crusades, repression of women and the LGBTQ+, the Holocaust, and almost every other bad act in history. The reason is that it's a really easy to gain public support for evil things.
4. Christianity justifies slave morality. Slave morality is the morality of the weak that gives them a personal justification for not actualizing their desires and trying to better themselves. If they don't have to act on their desire and better their life because they tell themselves this is the life that God wants them to live. A Christian doesn't have to justify to themselves why they're not fighting to have better living conditions if they tell themselves they're just being meek. Christianity inherently stops self betterment this way.
1. Any loneliness comes from the systematic discrimination and exclusion of atheists. They are tied for last place as the most disliked group in America (3) I would say this further proves that Christians like to exclude groups of people, but also that atheism is not the cause for loneliness, but unfortunately is dealing with the social symptoms of being a minority group. Also, atheists are 16% more likely to find meaning in hobbies and activities, (4) meaning they build communities outside of religious values, but not that these communities aren't formed.
2. I would argue that being able to use substances as you please without some outside moral code forcing to to not make these decisions leads to a better self. My opponent doesn't really say why drug use is inherently bad, and my answer would be that it isn't. There's millions of people that drink alcohol and smoke marijuana in moderation, and to say that this is inherently bad isn't true.
3. 19% of atheists meditate, (5) so I wouldn't say this is inherently relevant to showing Christians as better than atheists.