Do your colleagues code outside of work?
Considering that you don't do any FP at your company, then getting anyone to learn a new language/paradigm when they don't do anything outside of their direct work tasks will be next to impossible.
If they do, then find interesting projects that they'll like that are related to functional programming and show them. You're not in a position to mandate a change, so you'll have to sow the seeds if interest on a personal level. This is how I was introduced to it - granted, by my best friend who happens to work with me.
Outside of that, most people write in-house tools to make small tasks easier. Try to write some of them in a functional language. Anyone who wants to see the code will be exposed to the (hopefully/possibly) beauty of the code and will likely ask you about it when they do. That is an opportunity to sell the idea.
Remember, there are functional languages that will work on your stack (scala/closure both run on the JVM). It's not "purely functional" like Haskell is, but it's a good start on a long journey.
If you have any control over hiring, hire people who have some functional experience (or are at least interested in functional programming).
And finally... you might be at the wrong company if you're that passionate about writing functional code. You're not going to change the way your entire company writes software - especially if they're making money and even more especially not in any reasonably short amount of time.
This is all about selling it to the devs... management is a whole other beast entirely.