"You don't need anything excessive," Rapp said. "If you have excess in your life, it can be a distraction. Just get rid of it."
The Catholic Church teaches that the evangelical counsel of poverty – along with chastity and obedience – is proposed by Christ to all disciples, as a way of growing in the Christian life and cooperating with grace.
Rapp pointed to Mark 10, in which a rich young man asks Christ what he must do to inherit eternal life. In addition to following the commandments, Christ instructs him to "Go sell what you have, give to the poor…then come, follow me." But Scripture says the young man went away sad, "for he had many possessions."
Material possessions are not inherently evil, Rapp clarified. But when we become attached to them, they go from being necessary items that help us in life to becoming "a real detriment, a distraction from the priorities" we should have.
Members of religious orders take a vow of poverty, which is generally lived in a very radical way, while canon law suggests that diocesan priests should live a simple life and give away any excess that they have to the poor, Rapp said.
"I think that's a pretty good general rule for everybody."
Determining what is excess in one's life is a matter of personal discernment, the priest said. In his community, members are guided by the principle, "Start with nothing, and keep only what you really need."
Other guidelines include trying to limit belongings to what can be packed in a car – fitting for the life of mobility to which priests are called – and asking the question, "Have I used this within the last year?"
"If you haven't, you might not need it. You might not use it in the next 20 years," Rapp said.
While they are purging, the Denver Companions pray in gratitude to God. This is a key part of the process – acknowledging that everything they possess is a gift from God and asking him to help them see what they should be letting go of and detaching themselves from.
"We do the purge communally, so you show everybody what you have. There's a certain accountability to it," Rapp added. Their fellow priests can also challenge them on specific belongings, inviting them to reflect on whether they actually need a certain item.
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"We don't actually need what we think we need," he said.
For lay people, especially families with children, the criteria for what to keep may look different.
"It is really difficult when you have children of various ages to keep possessions simple, because there are various needs in the home happening all at the same time!" said Alicia Hernon, a mother of 10 children and the co-director, alongside her husband, of The Messy Family project and podcast.
"It's hard for moms to give away clothes when you know you will have a child who will wear those clothes or play with those toys in just a few years," she told CNA. "Yes, I would love to get rid of all the extra toys and clothes, but not if I will have to replace them for the next child hitting that stage just a short time from now."
"For us, living simply means that I had to have an effective storage system for clothes and a set time to take them out when needed. It also means that we had to do the same with certain toys."
But while simplicity may look different for families – especially large ones – Hernon said there are still benefits to a simple lifestyle, especially because it helps family members "focus on the people around us."