During a conversation with my friend about cosmological argument for God, friend told me that cosmological argument is not even true because causal principle is outdated and not needed in modern physics. After the conversation, I searched for that by internet and found out Russell first argued like that and many contemporary philosopher of physics agreed that causality is at least not needed in our fundamental physics. I think if this kinds of argument succeed, then causal principle is undermined and as a result cosmological argument cannot be hold. So my question is, how do proponents of causal principle and cosmological argument answer to that?