The available evidence shows that Charlie Kirk, a conservative activist, was fatally shot in Utah, not stabbed in Idaho by a supporter of himself.
A male victim was stabbed to death by a Charlie Kirk supporter in Idaho.

Charlie Kirk shooting death – what we know so far - Charlie Kirk shooting | The Guardian
Source: theguardian.com
Key Evidence
Multiple news outlets including The Guardian, CBS News, and NBC News report Charlie Kirk was shot dead at a Utah university event.
theguardian.comtheguardian.comCharlie Kirk shooting death – what we know so far
cbsnews.comcbsnews.comCharlie Kirk shot and killed at Utah event; manhunt for shooter continues for...+1 more
Wikipedia and The New York Times confirm the location as Utah and describe the incident as a shooting.
en.wikipedia.orgen.wikipedia.orgKilling of Charlie Kirk
nytimes.comnytimes.comAfter Charlie Kirk’s Death, Voters Agree Something Is Wrong in US
There is no credible source mentioning any stabbing or an incident in Idaho related to this case.
What the Evidence Shows
The claim that a male victim was stabbed to death by a Charlie Kirk supporter in Idaho does not match any verified reports from multiple reliable sources. Instead, all credible sources consistently report that Charlie Kirk himself was the victim of a fatal shooting at an event held at Utah Valley University in Orem, Utah. There is no mention of stabbing or Idaho in connection with this incident.
The suspect involved was apprehended in relation to the shooting, and the event has been widely covered as a politically charged shooting rather than a stabbing. Additionally, none of the sources indicate that the attacker was a supporter of Charlie Kirk; rather, the focus is on the shooter being responsible for killing Kirk. Some sources also discuss the aftermath and political reactions but do not support the stabbing claim or location stated in the input.