The lack of an 'off-switch' on the human body makes it obvious to me that we weren't "intelligently designed". We were sculpted by an uncaring, unintelligent process over billions of years (something intelligent wouldn't take so long), a barbaric meat grinder gauntlet. Additionally, the argument that we're "supposed to live", no matter what, falls flat for three reasons:
- According to who? "Supposed" necessitates an intentional agent. God? Where is he? He's playing hide and seek or...?
- Even if there's a god who intends for us to live at any cost, why should we obey that god? Just because they created us and hold a lot of power over us, and might punish us for disobeying? Not very convincing.
- If we were truly designed to live (by a being with apparently PERFECT knowledge no less), then why do many of us will to die, at any moment of our lives? Isn't that terrible design?
From here, theists usually rely on the free will defence to explain suicidality. But free will is an impossible joke.