There is a meeting in my area entitled "We Agnostics". It is the conscience of this meeting that they never say the Lords Prayer or the Serenity Prayer and instead recite the AA Pledge at the end..."I am Responsible".
Someone attended this meeting regularly and insisted on reciting the Serenity Prayer, claiming that these other members were not practising "Real AA". She was mistaken.
Individual members may have certain beliefs, but noone can be compelled to believe anything. Pictures of Jesus in meetings are not part of any recognised guidelines or approved literature. ..it may just be the conscience of that particular group.
P