Christ's mother, the Virgin Mary is an "icon" for the forgiveness of sinners by the Catholic Church, Pope Francis tweeted on Friday."Mary is an icon of how the Church must offer forgiveness to those who seek it," Francis wrote on Twitter.His nine-language @Pontifex account has over 22 million followers.At an event earlier, the Pope also said the divine calling of priests is to serve the poor and those living on the margins of society."You were called and consecrated by God to stay with Jesus and to serve Him in the poor and in those excluded from society," Francis told priests from the Sons of Divine Providence Catholic missionary order, and warned priests not to let their faith "become an ideology", or their charity a mere "philanthropy"."There is so much need for priests and nuns who know how to go beyond the confines of charitable institutions and bring the balm of Christ's charity far and wide."Your heart... needs to go out to bring the mercy of God to all, without distinction," Francis said.