Vatican issues first text co-written by two popes

The Vatican on Friday issued an unprecedented religious text co-written by Pope Francis and his predecessor Benedict XVI in which the two popes said faith should serve the "common good" but restated their opposition to gay marriage.

Francis paid tribute to pope emeritus Benedict XVI in the encyclical, saying that the ex-pontiff had "almost completed" the text before stepping down in a historic move this year and that he himself had merely added "further contributions."