“The march of Christians will not stop,” Abbot Francois Luyeye said to loud applause at the packed Notre Dame cathedral, the capital’s largest church.
“We have a sacred duty to continue the good fight for the emergence of a new Congo in which the right man will be in the right place,” the priest said in a sermon.
The mass was held in memory of the victims of a January 21 march in Kinshasa when security forces opened fire on Catholic-organised rallies against Kabila. The United Nations reported seven dead, the government two.
Luyeye called for more marches which he said “will demonstrate you are the church, even if it displeases those who believe that faith must remain shuttered in the sacristy.”
Kabila hit out at the church’s political broadsides at a January 26 press conference.
“Give to Caesar what is Caesar’s and to God what is God’s,” he said.
“When you try to mix the two it is dangerous. The result is always negative.”
Effigies of five of the dead were placed before the cathedral altar while video footage of the violence were shown on a screen.
Several diplomats, opposition figures and activists attended Friday’s mass led by influential Kinshasa bishop Laurent Monsengwo.
Kabila, 46, has been in power since 2001, at the helm of a regime widely criticised for corruption, repression and incompetence.
His term in office expired in December 2016 but he has stayed on, stoking a bloody spiral of violence.
The church, which brokered a deal for him to remain in power provided new elections were held in 2017, wants him to pledge to stand aside in the presidential vote set for December 23 this year.
Meanwhile former prime minister Samy Badibanga called Friday for an international humanitarian aid conference to raise $1.68 billion (1.37 billion euros) to ease the country’s plight.