I believe that there is a First Cause. Something caused the material universe to come into existence. What I don't believe is that a religionist can describe in detail the characteristics of the First Cause. I don't believe that the "Creator" or "God" or whatever you want to call is what has been described by Christians (or any other religionist).
The First Cause is external to our universe. Therefore, we have no frame of reference to comprehend the First Cause. It would be like asking a line to understand a cube. The line has no frame of reference and the cube is extra dimensional from the line's point of view. We are the line, the First Cause is the cube.