Anyone's "belief system" isn't going to be shared by others no matter what it is. As I answered to Kit, I don't ascribe to any church or any form of "organized" religion or doctrine after formerly being a member of the Pentecostal church. No time for typical "evangelical" denominations and after those experiences I practically became an atheist for a while so where it comes to introspection you are way off the mark.
You don't seem to have introspected enough to be able to (or to feel confident in being able to) articulate what you believe when asked. If you really have very few assumptions, then it should be clearer to state on whatever is left over. I'll try to give an example,
I believe that there is a single Creator (God) of all that exists.
That would be a starting point, but given only that it could also mean that it is an invisible God that no one has ever seen, heard from, in knowledge of his will, or that he even perished and is gone for ever. It also says nothing of what the character of this believed God would be, which could range from our ultimate standard of goodness to capricious random acts of whimsical evil.
I'm not saying that defining what we believe to others is always an easy task. A lot of people take shortcuts such as "I believe in the JKL and XYZ creed and confession of faith" (yet they may not be able to explain or defend these complex statements if asked.)
If I were being asked for a summary of what I believe, I would also say that I believe that God was manifest in the flesh and we called him Jesus, and that he intended for us to have his words in this day through what we call our scriptures. More definition might be provided depending on who was asking and for what reason. The particular reason I had in asking was to determine if there was any point of authority upon which we might already agree.
For example, if you reject the Bible then I can only use scripture to explain my rational, rather than as a basis for your own. If you believe you have revelation from a personal vision, that would also be helpful to know. I remember a TOL member who did claim revelation from personal visions...