Lisa, the line you cite is indeed very frequently attributed to Burke, including occasionally by scholars (and at least once by Ronald Reagan in a speech.) But it is nowhere in Burke’s published writings or correspondence, and in most of the forms in which you find it online it doesn’t really sound like Burke’s way of writing and talking (there are a great many variations on the precise wording, some closer to Burke’s parlance than others). “All it takes,” for instance, surely never came out of his mouth or his pen.
The closest genuine article is probably Burke’s statement in the Thoughts on the Cause of the Present Discontents that “When bad men combine, the good must associate; else they will fall one by one, an unpitied sacrifice in a contemptible struggle.” Vaguely similar, though really the subject and point are rather different.