The decision, which took effect July 1, ends a three-year "formal partnership" between the two organizations that share many goals in their missions, including numerous peace and justice components.
The dissolution of the partnership, prompted in part by budget limitations, will save Pax Christi a $30,000 annual fee paid to JustFaith Ministries.
The peace group shared its partnership with Pax Christi International, which is in negotiations to maintain the affiliation.
As part of the partnership, JustFaith promoted Pax Christi's mission in program materials used primarily in small groups in parish settings.
Pax Christi was also invited to send representatives to promote the organization at local JustFaith program groups, held near the end of each JustFaith program.
To date, more than 4,000 JustFaith programs in more than 40 states have registered approximately 40,000 people.
"Our hope was to increase awareness of PCUSA and increase membership" through the JustFaith partnership, said Sr. Patricia Chappell, a Sister of Notre Dame de Namur and executive director of Pax Christi. "And what we came to realize is that is not happening."
JustFaith founder and president Jack Jezreel said Pax Christi's decision is disappointing and said the affiliation resulted in "a lot of exposure" for Pax Christi in JustFaith programs.
Fewer than 200 people attended the peace organization's conference last month in Atlanta.
"Our funds are very limited right now," Chappell told NCR.
The organization hoped people coming through the JustFaith programs would take the next "natural step" and join Pax Christi, Chappell said, but that is not happening.
Jack McHale, a Pax Christi member from Virginia, backed the decision to affiliate with JustFaith during his time on the group's national council.
McHale, whose parish, Our Lady Queen of Peace in Arlington, includes both JustFaith programs and a local Pax Christi chapter, said the decision to cut formal ties with JustFaith was shortsighted.
"I'm terribly disappointed," McHale said. "Why couldn't we figure out a way between two really good organizations to make this work?"
Marie Dennis, co-president of Pax Christi International, sits on the JustFaith board of directors.
Dennis said the decision for the group to end its formal relationship with JustFaith was "the best decision Pax Christi USA could make at this time based on the information they had and their assessment of where to put their resources."
In addition to Pax Christi International, JustFaith partners with Catholic Relief Services; Catholic Campaign for Human Development; Bread for the World, a Christian citizens lobby group that works on global hunger relief; and Maryknoll, the Catholic missionary order.
Catholic Charities USA also serves as a JustFaith "supporter," Jezreel said.
Dennis said Pax Christi International does not have the funds to maintain a full partnership with JustFaith, but they are in negotiations with JustFaith to "continue a collaboration different from a full partnership."
Dennis said she is also committed to helping Pax Christi and JustFaith stay connected on some level.
"I think JustFaith does really wonderful work," she said. "I think there will be a way for Pax Christi USA to continue to cooperate with JustFaith. I think Sr. Patty and [Jezreel] are both very committed to keeping the relationship alive."
Although the formal partnership has ended, Jezreel and Chappell say both organizations will continue to work together in some capacity.
"We see Pax Christi as a huge ally for us," Jezreel said. "We're not withdrawing any support for Pax Christi. I still believe that there is great potential in linking the formation work and constituency of JustFaith Ministries with the activism and vision of Pax Christi USA, and we will continue to explore that potential in both formal and informal ways."
Chappell also said she is also open to "re-evaluating" the decision in the future. "We certainly will continue to support the work of JustFaith ministries," she said.