The broadside from James Dobson, the head of the conservative Focus on the Family Group, threatens to blunt Obama's attempts to court evangelical voters, who traditionally vote overwhelmingly for Republicans. "I think he's deliberately distorting the traditional understanding of the Bible to fit his own world view, his own confused theology," The Independent quoted Dobson, as saying. In his radio show, Dobson accused Obama of twisting Biblical passages like Leviticus, which Obama said suggests slavery is acceptable and eating shellfish is an abomination.
He took exception to Obama stating that Jesus's Sermon on the Mount was "a passage that is so radical that it's doubtful that our own Defence Department would survive its application".
By supporting abortion rights, Obama was trying to govern by the "lowest common denominator of morality" and supporting "a fruitcake interpretation of the Constitution," Dobson said.
Dobson's ire was concentrated on a June 2006 speech that Obama gave to the liberal Christian group Call to Renewal.
The Obama campaign had previously indicated that the candidate would like to meet Dobson.
The Focus on the Family leader has said he could not vote for Senator John McCain, the Republican nominee, because of concerns over his conservative credentials.
McCain had wanted to meet Dobson, but the evangelical leader said he would only meet the Arizona senator if he travelled to his Colorado headquarters.
Christian evangelicals could decide the 2008 election if significant numbers of them defect to Obama - or even if they decide to stay at home rather than voting for McCain.