Princess Shcherbatsky has agreed to hold the wedding between Levin and Kitty before Lent (which, incidentally, does not start on Ash Wednesday, as it does in the Catholic Church. In the Eastern Orthodox tradition, Lent begins on "Clean Monday," the Monday of the seventh week before Easter.
On the condition that Kitty's trousseau (read: things a bride needs, kind of like the stuff people get from a marriage registry today—linens and dishes and so on) is divided into a large part and a small part.
The small part will be ready in time for the wedding, and the large part will be sent later. The bride and groom plan to depart for the country directly after the wedding.
Levin remains on cloud nine. He does anything anyone tells him to do, because he's just so ecstatic.
In order to get married, Levin has to take the sacrament of communion. He feels awkward about this, since he is ambivalent about religion. He doesn't not believe in religion, but he doesn't believe in it either. (By the way, taking communion in the Eastern Orthodox church involves a fairly strict sequence of prayer, confession, and fasting.)
It strikes Levin as wrong to swear his faith in a religion he's not into right when he's feeling on top of the world.
At the end of the process, Levin tells the kind old priest that he has doubts about all the teachings of the Church, and that sometimes he even has doubts about the existence of God.
The priest remains unruffled.
Afterward, Levin is happy that he didn't have to tell any lies through the course of his confession —and that it's over with.