Why does Erastil send suicidal followers to hell? Isn't damning people to Avernus an act that's considered evil, especially if such acts can happen out of depression?He doesn't. None of the deities send souls anywhere. That's Pharasma's job, and is part of the soul judgment process she does. That's also why she's neutral; she doesn't favor one fate over the other, and judges each soul on their own merits against their own lies.
Pharasma is also capable of wisdom in her decisions. If a soul of an Erastil worshiper who commits suicide from depression stands before her... she'll weigh ALL factors of that soul's life before deciding. Suicide doesn't automatically mean you're "going to hell" in Pathfinder, and if we published something like that, it was a mistake that we should fix.
It's not uncommon for an individual author to let their own personal religious and philosophical beliefs color their writing. Part of a developer's job when we devlop an author's text is to ride the line between preserving the author's voice and changing what they wrote so that the published text represents Paizo's voice in presenting Golarion. (We didn't do a particularly great job moderating Paizo's voice for the deities around the time most of us were distracted by the overwhelming task of getting the RPG off the ground, for example, such as articles that appeared on deities in the Council of Thieves or Kingmaker Adventure Paths.) If we HAVE published something that says "If you worship Erastil and commit suicide, Erastil sends your soul to hell," then please let me know so I can make sure we don't make that mistake again—there's TWO mistakes there, in fact. You don't go to hell if you kill yourself, and Pharasma's the one that sends souls to their afterlife, not any other deity.
There's a blurb about it in Kobold Quarterly #22. I always found it incredibly weird that a good deity would perform such an act, so knowing that they're not actually performing such horrid acts is relieving.
Several religions enforce strict tenants against suicide. In many of these lawful religions—Erastil’s and Torag’s faiths, for example—suicides are denied a place in the god’s home in the afterlife, instead being condemned to Hell—specifically the plains of Avernus. Such discarded souls wander the Iron Wilderness, untouched by the pressgangs of infernal dukes that drag souls to Hell’s deeper depths. Instead, they wander in eternal hopelessness, facing endless pursuit from Avernus’s flocks of achaierai and packs of hellcats, or finding their way amid the mind-bending terrors of the Promised Land.