Yes, this is fine for the believer. We can all certainly nod our heads in agreement. But from the non believer's standpoint, this isn't found within his world view. These are conclusions that are derived from some sort of argument. We can't simply repeat to ourselves things that we already believe and neglect to realize that the non believer is not a member of the club.
Circularity does indeed seem unavoidable.
The charge of circularity only works if we allow ourselves to fall into the trap of thinking that all beliefs require logical proof or argument. The very concept of a presupposition is the recognition that not all beliefs require such argument. I believe this opens the door for the non theist to validate his own view. If a presupposition is a concept that does not require substantiation and is a self-evident truth, a properly basic belief, and the Christian offers God as his foundational presupposition, the non theist could just as well maintain an unknown ground as his foundational presupposition. In his view, there may be no reason to suppose that a known ground necessarily exists.