That's one example of a nonlinear function, yes. You also have (eˣ)/(1+eˣ), or (e²ˣ-1)/(e²ˣ+1), or a host of others which don't contain anything if-like at all.
I don’t know what point you’re trying to make. Neural nets are fundamentally different from rule-based systems. The fact that one of the non-linear functions which is sometimes used in neural nets can be implemented using an if statement seems utterly irrelevant.
