A "Viking" was a a warrior who went raiding abroad. (See the Jorvik site for more on this.) They were probably the most famous medieval Scandinavians, but they were a small subset of all the Norse people.
Having said that, warrior gods would have been closest to their hearts, and Michael Enright has theorized that the rise of the god Odin was linked to the cultural and religious rise of warbands with a charismatic leader. (You'll notice on the show Vikings that Ragnar Lothrbrok has a close connection to Odin.)
So while farmers would have mainly worshipped Frey or Thor, and merchants and sailors probably focused on Njord, warriors certainly focused on Odin.