Well, I can't speak much for Common Lisp, but you couldn't be much more wrong for Scheme--Scheme is easily one of the easiest language to learn, full stop. The intro CS course at my university used to be taught in Scheme and people with literally no programming experience could get the hang of most of the language in the first couple of weeks.
The only reason some people view it as difficult is that it is very different from the C-like languages they're already familiar with. Once you've learned one of those, the others are, of course, very easy to pick up. Not because the languages themselves are simple but because they're similar. Scheme, by comparison, has a very different--and much more regular--syntax and very different ways of doing things.
Besides, C is relatively difficult to learn: there are a whole bunch of low-level concepts (pointer arithmetic), a large amount of syntax and a ton of edge cases and undefined behavior. Not to mention the preprocessor. It takes much more effort to get even a basic result with C than it does with another language like Scheme.
What is difficult about programming in Lisps is the same thing that is difficult about driving 911's - doing so in the manner that experts do requires a radically different mindset. If you've seen 911's slinging oversteer around a road course and schemers...well writing scheme - it's apparent that neither thinks about driving or programming like the people against whom they are competing.
The only reason some people view it as difficult is that it is very different from the C-like languages they're already familiar with. Once you've learned one of those, the others are, of course, very easy to pick up. Not because the languages themselves are simple but because they're similar. Scheme, by comparison, has a very different--and much more regular--syntax and very different ways of doing things.
Besides, C is relatively difficult to learn: there are a whole bunch of low-level concepts (pointer arithmetic), a large amount of syntax and a ton of edge cases and undefined behavior. Not to mention the preprocessor. It takes much more effort to get even a basic result with C than it does with another language like Scheme.