When you kill the final boss after completing all the puzzles, you'll receive the weapon.
To get the Divinity, you'll need to complete a series of small puzzles spread throughout the Garden of Salvation Raid. With Divinity's blue bubble, you can achieve critical damage without the risk of missing. It's also an excellent choice for one member of a fireteam to use during a Raid boss, as bosses such as Taniks from the Deep Stone Crypt (don't miss my guide on how to beat every Deep Stone Crypt encounter if you haven't done the new Raid yet) have a weak spot that's difficult to hit normally. Therefore, for strong enemies like Champions, Divinity is phenomenal. This is because this trace rifle has the unique ability to debuff enemies by covering them in a bright blue bubble that stuns enemies and makes all damage done by allies critical.
The Divinity is one of the best and most valuable tools for players to have in their arsenal, especially if they frequently play Raids and high-level Nightfalls.