The case of atheism is a practiced and oft repeated one. I've never been totally convinced myself, as I still have an inability to explain consciousness in any other way than the spiritual that makes any sense to me, but I doubt I'm going to be able to convince others of that. I'm not going to duel with dualism here.
In the new All New X-Men however, Beast makes his position on the matter clear. Except it's complete nonsense. Not for anyone reading the book, but for anyone living in the Marvel Universe.
This is a man who has served on the Avengers with Thor, God Of Thunder
And even if his godlike status can be dismissed as a powerful alien race, he's also served with Valkyrie…
Who can transport people back and forth from the land of the dead. Even if Beast doesn't believe it exists,
He's had his soul cleansed by Illyana's sword. Even if he's not meant to have a soul.
And he's seen New York infected by demons from Hell. Even though there isn't meant to be a hell.
Basically, the only logical scientific position to take in the Marvel Universe is that there is an afterlife. And he should perform experiments there to understand its true nature.
Unless of course, Marvel NOW! was a reboot after all and all the above never actually happened…