Levin, thus far ambivalent about religion, despite the fervor present throughout Russia, must attend confession before he can be married, bringing about the most interesting musings and discussions on religion and faith in the novel so far.
Levin confesses his doubts in the existence of God to the priest, and is surprised by the nonchalance of acceptance, and the perhaps arrogant belief that this will (and must) pass. But through this we discover more about Levins fears and beliefs, his willingness to try to believe something he doubts, in order to please his family and give (potential) children a proper upbringing.
The wedding is a multi-chapter detailed success, and the two retreat to the country where there is an endearing adjustment period, as neither of the innocents know what to expect from married life, and find themselves disappointed in some aspects and unexpectedly surprised in others. It is perhaps not until they are called to the deathbed of Levin’s brother that Levin (and the reader) truly knows the value of the young woman he has married.
Part 5 is also the first time we see Anna happy. Or mostly happy. Living in Italy with Vronsky, she is relaxed and at peace with her choices. Her only remaining sorrow is the separation from her son. She attempts to make up for this by showering attention on her infant daughter, but realizes she simply does not love her as much as her first-born (as a second born daughter, I found this mildly disconcerting). Vronsky on the other hand, finds that now that he has everything he wanted he is bored and unhappy. He does love Anna still, but misses the excitement of their previous existence.
When they return briefly to St. Petersburg, Anna attempts to see her son, and when refused, she sneaks into her former house with the help of servants, angering Karenin – whose new best friend the countess Lydia Ivanovna is as fervent (and frightening) in her religious faith and Levin is doubtful.
The overlying themes here are definitely religion and marriage/relationships. First, the contrast between Levin and Lydia Ivanovna in their approach to the church, and how it shapes their outlook on life. Second, the approach of the men to their relationships. Both Levin and Vronsky find themselves discontented when they finally get what they wanted from love. Levin, as the stronger character, deals with this much better, adjusts and lets go of silly expectations, and finds happiness. Karenin doesn’t so much miss his wife as he misses the role she played in his life, and is happy to let another woman take over the role.