LOS ANGELES — Last year Dave Wilkinson asked God for guidance. He wanted to know what he could do to better fight abortion.

Wilkinson, an evangelical pastor, runs three Ventura County, Calif., pregnancy clinics that encourage women to choose alternatives to the procedure. He believes the prevalence of abortion is the biggest test Christians face. "It's probably one of the things that American Christians are going to have to stand before God and answer for," Wilkinson said. "He will say, 'You, as Americans, what did you do to fight abortion?' "

Wilkinson, a 55-year-old Simi Valley resident with a gray beard and a calm manner, said God answered his prayers with a directive to "go where the battle is." So last September, he brought his work to Watts.

Every Tuesday since then, Wilkinson and a handful of like-minded Christians have driven into the city in a donated motor home equipped with an ultrasound machine and parked it near the Imperial Courts housing project.

Watts is one of the city's poorest neighborhoods, and abortion rates tend to be higher in low-income areas, according to the nonprofit Guttmacher Institute, a leading authority on sexual health issues. For four hours, Wilkinson's group offers free pregnancy tests, using the ultrasound to show women images of their fetuses and leading prayer-filled counseling sessions in which they urge the women to keep their unborn babies.

Frequently, the encounter becomes a religious experience.

"It can be a real catalyst for people finding God, or refinding God," Wilkinson said. "Because of the crisis they're in, they're more open — and that's when we introduce God."

The bright purple motor home is hard to miss. It's covered with stickers, including a large one that says, "All services are free!" Most of the $40,000 for the ultrasound equipment came from Focus on the Family, a conservative Christian group based in Colorado Springs, Colo.

Last week, Briana Lares, a high school student, decided to stop in with her boyfriend after passing the RV on her way to her Imperial Courts apartment.

Briana knew she was pregnant and had come for the free ultrasound. She sat down on a soft couch across from Joyce Sexaur, 55, one of the counselors at Wilkinson's Community Pregnancy Clinics.

Briana, who turned 17 that day, said she had an abortion last year because her boyfriend was in jail at the time and she worried she wouldn't be able to support a child alone. The abortion had angered him, Briana said, and this time she was going to keep the child.

"I'm so happy you're making this decision," Sexaur told her. "Now, do you have faith?"

"I don't really know what I am," Briana said. "But I have accepted God in my heart."

"Briana, that's going to really help. Because life can be really hard, but God will be there for you, and Briana, I believe God has a plan and a purpose not only for you but for your baby, too," Sexaur said.

Sexaur and the others who work at the mobile pregnancy clinic share a world view centered on one basic idea: that life starts at conception and is a gift from God.

"This is spiritual warfare," Wilkinson said. "It's a good versus evil thing. Jesus came to give life, and the devil takes it."

His passion on this front was sparked in 1975, when his San Fernando Valley church screened a film by Francis Schaeffer, an evangelical pastor who was one of the first antiabortion activists. He was further inspired several years later when classmates at a seminary in St. Louis staged protests and other acts of civil disobedience at a local abortion clinic.

While Wilkinson admired the brazenness of their work, it didn't suit his disposition. In two decades as a pastor at various Simi Valley churches he always preferred one-on-one counseling to standing before an audience and preaching.

He believes the pregnancy clinics are a more compassionate way to urge women to see abortions as he does. In January, Wilkinson's operation expanded. The mobile pregnancy clinic now makes weekly stops near L.A.'s MacArthur Park and in Oxnard, Ventura and Mission Hills.

In the RV, the emphasis is on birth.

"We want to educate them so they can see for themselves the miracle that this is," said Stephanie Loring, a 22-year-old home care nurse from Westlake Village who volunteers two days a week at the clinic.

"It's a way that I can serve the Lord," she said.