Tom Cruise, 55, and John Travolta, 64, are the Church of Scientology's biggest A-list names.
But according to former Scientologist Brendan Tighe, the Hollywood heavyweights have a long-running rivalry reportedly over the 2IC position under the Church's leader, David Miscavige.
In an explosive new interview with the Daily Mail, Brendan, who used to work as a security guard for the Church before he left the organisation in 2009, lifted the lid on the pair's beef.
"Cruise is the only celeb with a direct line to [head of the Church David] Miscavige. Travolta and Kirstie [Alley] don't have that," he told the publication.
According to Brendan, John is jealous over Tom's higher-ranking position than him.
"Travolta doesn't get anything free, no one is giving him absurd gifts like an airplane hangar, custom-made bikes, or over the top favours."
In 2008, the Top Gun star was awarded the Freedom Medal of Valor, which is the highest accolade a Scientologist can receive.
Brendan claims it tipped John over the edge and he "exploded in jealousy" over Tom's award.
"It's no secret that Cruise and Travolta despised each other. Travolta wasn't invited to Cruise's wedding with Katie Holmes, it told me everything. I can assure you Travolta doesn't recognise Cruise as a superior in any way. When Cruise got that medal Travolta was so p----d off," Brendan claimed.
Adding: "The closest person Miscavige had ever said that about before was Travolta, he was told by Miscavige that he was he most dedicated Scientologist and had introduced more members than anyone, so it was like getting his title stripped, he was jealous."
"Travolta dictated a scathing letter to his chauffeur, who had to write to Miscavige asking 'what the hell is this medal was all about?' I'd say it's a 50/50 split whether Cruise is even respected in Scientology."
"When Cruise got the medal, the Office of Special Affairs [the spy unit of Scientology] was on high alert for any comments that were negative - it built up a lot of resentment within the ranks of Scientology, they didn't think he deserved it."
The Church of Scientology has responded to the report, labelling it false and full of "unsubstantiated claims by an apostate who has a personal axe to grind."
"Oh, my god, I wouldn't have made it [without the church's support]. Honestly. The truth is, I didn't know if I was going to make it. Life was no longer interesting to me, so it took a lot to get me better. I will forever be grateful to Scientology for supporting me for two years solid, I mean Monday through Sunday," he said.