When Pope Francis touches down in Rome after his 10-day visit to Cuba and the United States, he will have little time to rest before he faces perhaps the biggest test of his papacy so far. Next Sunday he will preside at the opening of the 14th Ordinary General Assembly of the Synod of Bishops – better known as the family synod. The three-week event is the most hyped meeting of the world’s bishops since Vatican II. Media reports suggest it will lead to a dramatic change in Catholic doctrine on marriage. But that is highly unlikely. As Fr Thomas Rosica writes on page 23, “these international gatherings have never produced new dogma or overturned Church teachings”. What, then, is all the fuss about? Many observers see the synod as the climactic battle between those Vatican reporter Andrea Gagliarducci calls the “adapters of doctrine” and the “defenders of doctrine”. The adapters do not believe that their proposals, such as Communion for some remarried Catholics, actually overturn Church teaching. Rather, they say, the changes are simply intended to allow bishops more discretion in responding to local problems. They see this shift as a necessary adaptation to 21st-century realities that will make the Catholic faith considerably more attractive to millions of people. The defenders, meanwhile, argue that the Church already takes account of pastoral realities – and has done for two millennia. They believe that any “adaptation” of doctrine is, in the end, harmful towards those the Church is trying to help. But as Cardinal Wilfrid Napier points out on page 20, the contrast between the “adapters” and the “defenders” is simplistic. “No human being can possibly be fitted fully into the ‘conservative’ or ‘liberal’ box,” he writes. “Therefore, it is not only unfair but also untruthful to label people in this way.” Given the prevailing confusion about next month’s synod, it’s worth recalling why Pope Francis wanted the gathering in the first place.