Daniel Willis, co-founder and head of the Bible Society campaign, said posters reading "Jesus. All About Life" began disappearing from churches and homes shortly after they started going up in September while others were vandalized or damaged, The (Sydney) Daily Telegraph reported Wednesday.
The banners are part of a multi-denominational ad campaign that also includes TV commercials and bus shelter advertisements.
Willis said the disappearance of the banners, which each cost about $266, may not be a negative sign.
"It's are an indication of the impact the campaign is having," Willis said. "People are coming up to me and saying 'Everywhere I turn I see your sign.' There are some people who will want to souvenir one and other people might be offended by it but it gets people talking about Jesus."