Try the following:
The Cat Who Walks Through Walls
Starship Troopers - (wiki info) - likely the most controversial work in science fiction and his personal riposte to leftists calling for President Dwight D. Eisenhower to stop nuclear testing in 1958. “[Heinlein] called for the formation of the Patrick Henry League and spent the next several weeks writing and publishing his own polemic that lambasted ‘Communist-line goals concealed in idealistic-sounding nonsense’ and urged Americans not to become ‘soft-headed’. … Critics labeled Heinlein everything from a Nazi to a racist.”
Glory Road
Stranger in a Strange Land
I believe I’ve read more of his stuff, but that’s what sticks in my mind.
And yes, he can be pretty out there (which is ironic, or not, since he was a nudist)