First of all, Perl is the ultimate syntax hurdle, and I say this as a fan of Perl.
Second, if you're interested in functional programming, don't shy away from the languages you mention. Neither Common Lisp nor Scheme is particularly difficult (especially Scheme, whose syntax is almost nonexistent) and neither is purely functional.
Finally, read SICP.
I bet the human brain is a kludge. -- Marvin Minsky