How I understand it is that Lisp has syntax but lacks a grammar, the syntax is just very simple. Essentially the same as Forth and Tcl, everything is either a command or data, a result of the simple single pass left right parsing. But I am not completely sure I have things right just yet.

Edit: What I am saying is that in lisp '(' is actually a command and everything after it is an argument to that command. The syntax is command - arguments; this is what gives these languages their power, the simple syntax and lack of grammar allows us to define our own grammar. Hopefully someone will correct me if I misunderstand, I could be seeing Tcl and Forth everywhere since I have been primarily working with them lately.