Is atheism a scientific perspective?

[Angrboda]

In passing I would like to point out that language referring to function implies intentionality. Properly speaking, a materialist referring to functions in naturally occurring systems would be speaking figuratively.

Yes, that would be the begging the question which I referred to earlier. If all that function accomplishes is to smuggle in intentionality then it's no better than saying, "It's designed because I say so." There's also the argument that all use of function, intention or not, is figurative and so your point ends up being moot, at least in this context.