I used to think the same; couldn't really grasp LISP and had even more serious problems with pure functional languages such as Haskell. But the thing is, you can make up all sorts of excuses for not knowing something, but in the end, it's really just not knowing, no matter how good your excuses are.
Then I've spent some time learning LISP, practising it, trying to implement more and more complex algorithms in it and while I'm still not a pro, I'm starting to grasp the basics. And it made me a better programmer, even though at my daytime job I work as a C#/.NET programmer, the little LISP knowledge I have heavily influenced the quality of my code and I think for the better.
Then I've spent some time learning LISP, practising it, trying to implement more and more complex algorithms in it and while I'm still not a pro, I'm starting to grasp the basics. And it made me a better programmer, even though at my daytime job I work as a C#/.NET programmer, the little LISP knowledge I have heavily influenced the quality of my code and I think for the better.