In his first rally for his last-minute presidential campaign, rapper Kanye West ranted against abortion and pornography, argued policy with attendees and at one point broke down in tears during rambling remarks Sunday at a Charleston, S.C., wedding venue and convention center.

Mr. West, 43, a former supporter of President Trump, has left voters befuddled over whether his campaign is genuine, a publicity stunt to help sell albums and merchandise, or an effort to undercut Democratic candidate Joe Biden’s support among young Black voters in Southern states who traditionally vote Democratic.

In remarks that lasted just over an hour, Mr. West denounced abortion, swore, called on random members to speak, appeared to be putting forward policy proposals on the fly, and made comments that left even those in attendance muttering in disbelief.

Some on social media questioned the status of his mental health following the event. “Harriet Tubman never actually freed the slaves. She just had the slaves work for other white people,” he said at one point when discussing economic inequality.

The event, which was livestreamed on YouTube and carried on local television stations, did little to clarify whether Mr. West is genuinely attempting to win the presidency. The campaign he launched with a July 4 tweet already has missed several deadlines to appear on key state ballots.

At times, he even seemed to suggest he was more interested in disseminating a message than winning the presidency.

“Freedom does not come from an election. The freedom comes from you not loading up the pornography. The freedom comes from you not taking the Percocet,” he said at one point.

According to published reports, Mr. West needed 10,000 signatures by noon Monday to get on the ballot in South Carolina as an independent candidate for November’s presidential contest. But officials said neither Mr. West nor a representative for his campaign filed any petitions with signatures to the South Carolina Election Commission by the deadline.

His name will appear on the ballot in Oklahoma as an independent candidate. Only a $35,000 filing fee was required in that state.

In South Carolina, Mr. West appeared on stage with “2020” shaved into the back of his head and wearing what appeared to be a military-style vest. He argued that abortion should be legal but heavily discouraged, suggesting he would promote a policy as president that anyone who gives birth to a child be given $1 million “or something in that family.”

He referred to the Bible and Christian teachings multiple times, and broke down in tears at one point while describing how he was nearly aborted by his parents and said his wife, reality TV star Kim Kardashian West, insisted on having their daughter, North, “even when I didn’t want to.”

“The only thing that can free us is by obeying the rules that were given to us for a promised land,” he said. “Abortion should be legal be- cause guess what? The law is not by God anyway, so what is legality?”

The event carried few similarities with typical polished candidate events. The venue appeared to lack audience microphones, so Mr. West repeatedly told the crowd to be silent so audience members he called on could be heard.