I'm not real fond of the one-armed salute that is so prevalent in worship these days. I find it mildly alarming, to tell you the truth.
Your photo is a good example.
They're raising their hands, because they're "Sure".
Supposedly, that is some sort of "empowerment" gesture of defiance which feminists and alternative lifestyleoids have picked up along the way. Although the most familiar use of that we all remember with some horror (Germany: 1933-1945), it derives from older occult groups like the Vril Society and the Hermetic Order of the Golden Dawn. History is stranger than fiction... sometimes.