One of the authors who last week failed to win a plagiarism case against Dan Brown’s The Da Vinci Code has written a new book just in time for Easter to question the very tenets of the Christian faith.

Michael Baigent’s The Jesus Papers tries to strip Jesus of his divinity by claiming that he wrote letters to a Jewish court denying that he was the son of God.

The book was published in the United States last week on the same day as the first American paperback version of Brown’s novel.

The two immediately went head-to-head at bookstore tills with a print run of 150,000 for The Jesus Papers in hardback and one of 5m for the paperback of The Da Vinci Code, dwarfing last year’s 2m-copy release in Britain of Harry Potter’s latest adventure.

The Jesus Papers will be published in Britain next month, nine days before the film of The Da Vinci Code, starring Tom Hanks as a Harvard expert on symbolism on the trail of the holy grail. It will hit the cinema screens on May 19.

Had last week’s verdict at the High Court in London gone in favour of Baigent and another author, Richard Leigh, it could have led to the film being left in the can and Brown’s book, which has sold 43m copies worldwide, being withdrawn from sale. Baigent and Leigh claimed that Brown had stolen his ideas from their 1982 book, The Holy Blood and the Holy Grail. Instead they have been left with a £2m legal bill. (The third co-author, Henry Lincoln, did not take part in the lawsuit.)

However, cynics point out that, whatever the outcome of the legal action, the publishers cannot lose. Lee Curtis, an intellectual property lawyer from Pinsent Masons, said: “Given the fact that both books have seen surges in sales because of the publicity of the court case, the real winner in the case is Random House, which publishes both titles.”

The publicity surrounding the court case has seen sales of The Holy Blood and the Holy Grail, which had stalled at 3,500 copies a year in Britain, soar to 7,000 copies a week, a 100-fold rise. Similarly, The Da Vinci Code was returned to the bestseller lists with sales of 20,000 copies a week.

Baigent, who was not in court for the verdict, said last week that his new book explored how Pontius Pilate, the Roman procurator of Judaea, made a secret deal to save Jesus’s life because Christ had called on the Jews to pay their taxes. He added: “All that Rome required was that taxes were paid. Suddenly he couldn’t execute this man but he had to get him out of the way because he wanted peace in Judaea.”

The Jesus papers in the book’s title are two scrolls supposedly written in Aramaic and found under a house in the old city of Jerusalem in the 1960s. It is claimed they are letters written to the Jewish court, the Sanhedrin, by Jesus, saying he is not the son of God but is filled with the spirit of God.

Baigent also claims he has discovered information about a mysterious do*****ent that purports to provide evidence that Jesus was alive in AD45, more than a decade after the accepted date for the crucifixion. The do*****ent was supposedly seen by Alfred Lilley, canon at Hereford Cathedral, at a church in Paris in the 1890s but later vanished. Baigent believes it now rests in the Vatican.

Biblical scholars were quick to pour scorn on the claims.

Pierpaolo Finaldi, editor of the Catholic Truth Society which has sold out first editions of its own books that claim to crack The Da Vinci Code and offer the truth about Jesus, said: “All this seems far more far-fetched than the actual resurrection from the dead.”

Canon George Kavoor, principal of Trinity theological college in Bristol, said: “Michael Baigent needs to be a Nobel laureate for his imagination. But these books have created a huge amount of interest in the veracity of the gospels and whether Jesus existed or not.”

Margaret Tofalides, a copyright lawyer at the law firm Addleshaw Goddard, said that Baigent and Leigh had probably hoped for a quick settlement to make money rather than have to go down the high risk route of a full-blown trial.

“Unfortunately, it’s not an ending they would have written for themselves,” she said.