The main idea of the cartoon is fairly self-explanatory, although it might upset devout Catholics! However, the SMS abbreviations may not be clear to everyone. OMG stands for 'Oh My God', and LOL 'Laughing Out Loud'. The # symbol is called a hash in British English, and a pound sign in American. It is commonly used to create hashtags, or search terms, on Twitter.
The Pope has over 500,000 Twitter followers, but His Holiness hasn't tweeted yet. You can visit his Twitter home page here.