Suppose $P$ is a finitely additive probability measure on a space $\Omega$, and $X_1,X_2,X_3,\dots$ are i.i.d. random variables with mean 0 and variance 1. Is it true that for all $r \in \mathbb{R}$, $$\lim_{n\to\infty} P \left( \sqrt{n}\sum_{i = 1}^n X_i \leq r \right) = \frac{e^{-r^2/2}}{\sqrt{2\pi}}?$$
Basically I am asking whether countable additivity plays an essential role in the proof of the classical CLT.
See this question for a brief discussion of random variables in the finitely additive setting.