Interestingly, like most good ideas, it was taken out of context and perverted to the simplistic thinking of idealists. The actual line is plagiarized from a poem by Bertold Bretch
Why then the war will come to you!
He who stays home when the fight begins
And lets another fight for his cause
Should take care:
He who does not take part
In the battle will share in the defeat.
Even avoiding battle will not avoid Battle,
since not to fight for your own cause really means
Fighting in behalf of your enemy's cause.