Dakota Johnson has joined ISIS ... well, at least a character she played on "Saturday Night Live" -- and the Internet went CRAZY!

Check out the video ....Dakota's dropped off at the airport by her dad -- played by Taran Killam -- but instead of joining the army like the Toyota commercial ... she joins the infamously savage org.

Social media users blew up with anger ... with responses like:

- "I think it's safe to say I will never watch SNL or any of Dakota Johnson's movies ever again"

- "Dear #SNL, jokes about Isis are not funny. See how much you laugh when you have to see your loved one(s) being slaughtered. No respect."

- "Actually offended by the ISIS sketch... Is that seriously all you could come up with? @nbcsnl #SNL"

So we gotta ask ...