"I anticipate the worst is yet to come," Gibson said at the Global Pastors Network conference in Orlando, Florida.
The film, which depicts Jesus Christ's last 12 earthly hours, has been lauded for its historical accuracy - and accused of being anti-Jewish.
Gibson urged the pastors to take youth groups to see the film, despite the R rating it earned for the graphic depiction of the crucifixion, Gibson's publicist, Paul Lauer told the BBC.
"I hope I'm wrong, I hope I'm wrong," Gibson, a conservative Catholic, told the 3500 evangelical pastors.
Gibson will find out on 25 February, when the film is released on Ash Wednesday, the holiday that marks the first day of lent 40 days before Christians believe Christ was crucified.
The film "represents a disturbing setback to the remarkable achievements in Christian-Jewish relations over the past 40 years," the American Jewish Committee said on Thursday in a statement.
"Foremost among problems with the Gibson film is the inclusion of verse 27:25 from Matthew, the verse that blames Jews for Jesus' death and was repudiated by Vatican II in 1965," said the committee, some of whose members have seen the film.
"The film represents a disturbing setback to the remarkable achievements in Christian-Jewish relations over the past 40 years"
American Jewish Committee
Gibson belongs to an ultra-conservative Catholic group that does not recognise the reforms of Vatican II and celebrates mass in Latin.
The star of Lethal Weapon and Oscar winner for his role in Braveheart took more than $25 million out of his own pocket for the filming in Rome. He wrote the script, produced and directed the film and hired Jim Caveziel to play Christ and Italian actress Monica Belluci as Mary Magdalene.
Even Pope John Paul II weighed into the debate. While some US media reported that the pope praised the film, Vatican sources denied those reports on Thursday and confirmed only that the pontiff had attended a private screening of the film in December.
"We are deeply concerned that the film, if released in its present form, could fuel the hatred, bigotry and anti-Semitism that many responsible churches have worked hard to repudiate," Anti-Defamation League Director Abraham Foxman said.
"The film unambiguously portrays Jewish authorities and the Jewish mob as the ones responsible for the decision to crucify Jesus."
"It is going to be the 'go-to' film for Christians of all denominations who want to see the best movie made about the passion of Christ"
Editor of a Catholic magazine
The film attempts to portray life 2000 years ago, with characters who speak Latin and Aramaic, with English subtitles, earning the approval of conservative Christian groups.
"The film is going to be a classic," said Dean Hudson, editor of
the Catholic magazine Crisis.
"It is going to be the 'go-to' film for Christians of all denominations who want to see the best movie made about the passion of Christ."
More liberal institutions disagree. "We are really concerned that this could be one of the great crises in Christian-Jewish relations," Mary Boys, of the non-denominational New York Theological Seminary, told the Guardian.
The last film to kick up such a controversy was Martin Scorsese's The Last Temptation of Christ in 1988.