House Republicans and a handful of Democrats gathered in the Capitol on Monday for a prayer vigil honoring the life of the right-wing activist Charlie Kirk, in an unusual ceremony that reflected how his assassination has divided the two political parties.

Speaker Mike Johnson, Republican of Louisiana, used the occasion to call for civil political discourse of the kind that he said Mr. Kirk embodied, even as President Trump and top administration officials said his killing would prompt a vast crackdown on the left. The top Democratic leaders skipped the observance mourning the death of a figure who was reviled by many progressives because of his divisive remarks about race, transgender rights, feminism and Islam.

“The sadness for so many of us turned to anger,” Mr. Johnson said from the podium flanked by a photo of Mr. Kirk, his wife, Erika, and their two children set up in Statuary Hall for the vigil. “And there’s been a mixture of emotions, including fear.”

“What we do know about Charlie is that he would not want us to be overcome by despair,” the speaker continued. “He would want us to carry the message forward, to honor his memory and to expand the legacy that he left behind.”

Mr. Johnson sought to console members who had been close to the conservative activist, many of whom in recent days have shared how Mr. Kirk was key to shaping their political careers.

It is rare for vigils honoring individuals to be held inside the Capitol. Traditionally, they take place on the Capitol steps, including ceremonies marking the anniversary of the Jan. 6, 2021, riot by a pro-Trump mob, a vigil for two Israeli Embassy staff members killed in Washington, and a gathering for those killed or taken hostage in Israel on Oct. 7, 2023. Some far-right Republicans had called for Mr. Kirk to lie in honor in the Capitol, a distinction usually reserved for top officials or leaders of national stature.