There are several different ideas about what it means to fulfill the Great Commandment. Everyone agrees that the yinrih have been chosen to find other intelligent species, but different groups within the Bright Way have their own ideas about what that looks like.

When humans think of missionaries, they think of people travelling to distant lands to preach and accept converts. While this view is popular, it's not the only one.

Probably the simplest view is that the yinrih are to meet and interact with other species on a personal level, forging friendships with their new galactic neighbors. This is how Tod sees First Contact, which is fitting given his Commonthroat name means “Steadfast Friend”.

Another rather straightforward view, held by the Farspeakers, including Stormlight, is that in order to unite the yinrih's noosphere with those of other species, they must physically unite their computer networks together. Stormlight spends most of his time figuring out ways to bridge the Internet with the yinrih's ansible network.

Still another view says that the other species have important lessons to teach the yinrih. This manifests primarily in yinrih converting to various human faiths. There are hints that Iris espouses this view, or at least considers it as a possibility, given that she vehemently insists that the lapsed Pascal lodge with the human priest.

Others hold that the yinrih are to actively uplift less technologically advanced species. This is what Sunshine tries to do by researching human medicine.

As for Lodestar, he doesn't have a specific vision in mind other than the basic “find aliens”, but he decides to live out his vows as a Knight of the Sun among his new human friends by protecting the weak and trying to uphold justice.