(Redacted from a post on AIDL.)
Learning programming languages, like human languages, or generally different skills, is a way to enlighten you. LISP is a cool language because it does things differently. So sure, in that sense, Lisp worths your time.
On the other hand, if you do want to learn modern-day A.I. though, perhaps probability and statistics are the first "language" you want to learn well. As one member, Ernest Szeto said, nowadays A.I. usually use at least some probability-based logic. And if you think probability and statistics as a language, they are fairly difficult to learn on their own.
And yes, at AIDL, we recommend python as the first language, because it allows you to use several stacks in deep learning. You can also use R and java, but notice that there will be a gap between your work and what many people are doing.