How we cite our quotes:
"It [grace] is something I haven’t got; that I know. But I’d rather not discuss that with you. We’re working side by side for something that unites us—beyond blasphemy and prayers. And it’s the only thing that matters." (4.3.55)
Rieux identifies a commonality between himself and Father Paneloux. The motivation, he seems to say, doesn’t matter – they are united in their common ends: fighting the plague.
Paneloux held out his hand, saying regretfully:
"And yet – I haven’t convinced you!"
"What does it matter? What I hate is death and disease, as you well know. And whether you wish it or not, we’re allies, facing them and facing them together." Rieux was still holding Paneloux’s hand. "So you see"—but he refrained from meeting the priest’s eyes—"God himself can’t part us now." (4.3.62-4)
An interesting line to hear from an atheist, isn’t it? Short of Rieux experiencing a momentary religious conversion (unlikely), we think this is more to do with language. In his attempt to communicate with Father Paneloux, Rieux adopts the priest's religious terms to describe the kinship that surely in his own mind is secular.
Since joining Rieux’s band of workers Paneloux had spent his entire time in hospitals and place where he came in contact with plague. […] And constantly since then he had rubbed shoulders with death. […] But from the day on which he saw a child die, something seemed to change in him. And his face bore traces of the rising tension his thoughts. When one day he told Rieux with a smile that he was working on a short essay entitled "Is a Priest Justified in Consulting a Doctor?" Rieux had gathered that something graver lay behind the question. (4.4.1)
Rieux earlier accused the priest of being unable to speak of "truth with a capital T" because he hadn’t looked death in the face. Paneloux, since joining Rieux, has obviously become a different man; but does he still try to speak of "truth with a capital T?" Check out his second sermon and see.