Elizabeth Smart leaves the federal courthouse on Monday in Salt Lake City, Utah. ((Associated Press))

The man accused of abducting Elizabeth Smart was a crude, vulgar, self-serving person who used religion to justify his actions, including her kidnapping and rape, Smart told jurors at the trial of Brian David Mitchell in Salt Lake City.

"He was his No. 1 priority, followed by sex, drugs and alcohol, but he used religion in all of those aspects to justify everything," Smart said in a clear voice on her third and final day of testimony Wednesday.

Smart finished her testimony after just 15 minutes of cross-examination by a defence lawyer for Mitchell, an itinerant street preacher accused of taking Smart from her Salt Lake City home at knifepoint on June 5, 2002.

Smart, now 23, was 14 at the time of her abduction and was found nine months later after motorists spotted her walking with Mitchell in a suburb of the city.

Mitchell, 57, is charged in U.S. federal court with kidnapping and unlawful transportation of a minor across state lines. If convicted, he faces a life sentence.

Mitchell was not in the courtroom to hear Smart testify. As on each previous day of the trial, he was removed for disrupting the proceedings by singing hymns. He watches the trial on closed-circuit television from a holding cell.

Mitchell's defence attorneys contend he suffers from an escalating mental illness and holds extreme religious beliefs that lead him to think he is directed by God.

Smart gave a spirited rejection of that contention on the stand Wednesday, calling Mitchell a hypocrite.

"Nine months of living with him and seeing him proclaim that he was God's servant and called to do God's work and everything he did to me ... is something that I know that God would not tell somebody to do," she said. "God would never tell someone to kidnap her at knifepoint from their bed, from her sister's side ... never continue to rape her and sexually abuse her."

In previous testimony, Smart said that during the nine months she was held, she endured almost daily rapes and was forced to drink alcohol, use drugs and view pornography.