"purpose of the gathering" is correct and usable in written English.
You can use it to describe why a group of people have gathered for a particular occasion. For example, "The purpose of the gathering was to celebrate the company's 10-year anniversary."
The real purpose of the gathering was to encourage parents to read to children over the summer because the budget cuts had eliminated summer school.
The stated purpose of the gathering was to give Mr. Booker, already a Twitter fanatic, a seminar on social-networking technologies.
The purpose of the gathering was to address some specific questions, but what came through loudly for me was the reluctance of many to actually address them.
The purpose of the gathering, scheduled weeks earlier, was a daylong match of the classic Second World War-strategy board game Axis & Allies, in which the world's major powers battle for global military domination.
But the hoopla could not disguise the melancholic purpose of the gathering: to prepare the families of the soldiers for another lengthy deployment of their division to Iraq at the end of September.
The purpose of the gathering was not to dictate changes; Mr. Almodóvar only asked for a few tweaks in the script, like wiping out references to the Spanish dictator Franco (whom he reviled).
But one of the central purposes of the gathering is to motivate the party's most generous supporters to raise and give still more.
With security apparently assured and at least 7 doctors and 40 nurses on hand to deal with any medical problems, delegates have been able to concentrate on one of the purposes of the gathering: meeting other evangelists from around the world.
After the song ended down, the event's guests started to discuss the two purposes of the gathering – the launch of the 'Reimagine the Future: Innovation for Every Child' report, which is available entirely online, and the outcomes of the 'Imagine' initiative – in the context of the sudden disappearance of the energy we all rely on.
The purpose of this gathering is to create a welcoming space to engage with data and build data literacy skills in a fun, approachable way.
"The purpose of this gathering [was] to get people talking about how to get our needs met based on what we have," Jasahn Larsosa of This Hood of Ours told The Huffington Post.
