Matthew Rhys as Philip Jennings and Keri Russell as Elizabeth Jennings. (Craig Blankenhorn/FX)

This post discusses the events of the April 23 episode of “The Americans.”

Disguise and dishonesty are fundamental parts of the lives of Philip (Matthew Rhys) and Elizabeth Jennings (Keri Russell) in America. For most of us, bifurcating our lives, much less adopting as many identities as these two juggle, would be a shattering experience, impossible to keep up for long. In “Martial Eagle,” the couple are struggling, too. But the episode also does something canny, reminding the couple, and us, that normality does not always offer protection.

First, writer Tracey Scott Wilson takes her poison pen to Philip. In the previous episode, he convinced Elizabeth that they could simply tie up the man who gave them the passwords they needed to get onto the training ground. But once they are there, Philip has to commit yet another brutal, personal murder after his sense of mercy fails: The young man who sensed something wrong with Philip’s cover story will not stop shouting for help, even after Philip asks him to be quiet.

“Arpanet” showed us how this sort of necessity has taken a toll on Philip, and now he has done it again. But when Philip and Elizabeth get off the base, the episode only gets more merciless: The man Philip hoped to keep alive appears to have died from exposure. Nothing, it seems, will spare Philip from the cold, steel truth of his job, and he is quailing at the image.

At home, things get worse. Elizabeth and Philip, trying to show an interest in Paige, agree to go to church with her. “Are we going to start going to church every weekend now?” Henry wants to know. “Today’s a special service. It’s Teenage Sunday,” Elizabeth explains, trying to please both of her children. “Youth Day,” Paige corrects her carefully.

But during worship, Elizabeth has another moment, like the one in the previous episode with Henry, that reminds us and them how difficult it is to keep their lives separate. While the pastor talks about God’s mercy and generosity in sacrificing his only son, Elizabeth smiles encouragingly at her daughter, but worries at her husband’s face, locked in a grim rictus. Paige notices. And worse, thinking they are complimenting her, the pastor and youth group leader accidentally reveal that Paige gave her savings to the church’s mission work.

“They’re saving refugees, building houses! You guys don’t help anyone,” Paige spits at her parents when they get home. Philip reacts with a venom that suggests he fears it is true, ripping pages out of her Bible. Later, he tells Elizabeth: “I don’t need the speech. I know it’s war. This is easier for you.”

But is it? This is the closest they have come to discussing the events of earlier this season, when Elizabeth asked for rough sex with her husband, but ended up curled up in bed, a pale spiral wracked with tears. Killing is horrible, but given Elizabeth’s experience as an assault survivor, having sex for the cause is not much fun either. Where they differ is that Elizabeth still seems to draw sustenance from the cause, while Phillip feels increasingly alienated from it. Her punishment for Paige is a kind of catechism, a reinforcement of why she believes, and why her work feels worth it.

“Clean the refrigerator,” Elizabeth tells her daughter. “And after that, mop the floors and fold the towels in the basement … You want to be a grown-up? You want to spend money the way you want? Being a grown-up means doing things you don’t want to do all the time. It means working when you are exhausted, and almost never getting what you want when you want it. Your father and I never had a childhood. Nothing came easy for us, ever. You are so lucky, Paige. Mop and bucket are in the basement.”

While they are slipping at home, both Philip and Elizabeth seek comfort in disguise. As Clark, Philip has a chance to play the good, sensitive husband he has not been at home. And undercover in an Alcoholics Anonymous meeting, Elizabeth opens up to the sponsor much like she conned another mark earlier this season, saying she wishes she had an opportunity to be as good to her husband as he has been to her.

The greatest risk to their marriage may not be make-believe, though. Elizabeth is skeptical of any power that claims to be greater than capitalism and dialectical materialism. For years, a shared commitment to the couple’s work in that cause was the foundation of their relationship, even as it took a long time for a more genuine affection to rise from that poured concrete.

Philip’s attraction to the comforts of America has been the greatest threat to that foundation — until now. When Paige’s pastor tells Philip he really believes that anyone can be saved, Philip’s carefully applied mask collapses into the face of a real and devastated man. Last season, Philip stood firm against the protestations of a churchgoing woman whose son he poisoned for the cause, though he needed Elizabeth’s utter lack of sympathy for reinforcement. This year, he is more fragile, and the promise of salvation may pose a greater risk to him, and to Elizabeth, than any threats of hell.