The phrase "causal agent" refers to the thing or person that causes something to happen. It is the reason or force behind an event or action. Full definition
In turning the world upside down we call for a philosophy and a religion that make room for purpose as an effective causal agent in the universe. (religion-online.org)
The harmonious life is then the responsible life, in which one accepts one's role in the web as causal agent and chooses to act accordingly. (religion-online.org)
Most atheists I've spoken with have zero problem with there being an outside causal agent for the universe. (religion.blogs.cnn.com)