As he entered the back of First Baptist Church, Ken Medema's powerful voice filled the cavernous stone structure, quieting a packed audience as he walked toward the altar singing, "I will sing hallelujah till there's no more hunger and the story's told, I will sing, I will sing, I will sing."

That's just what he did for the next 90 minutes during a recent concert at the Northwest Washington church to benefit world hunger. The audience apparently liked the 40-year-old Medema's mixing of music with moral treatises, humorous twists on biblical tales and dramatic keyboard interludes.

"I couldn't believe the voice on that guy," said one man at the concert. "I kept saying 'where's the microphone,' but there wasn't one" as he walked up the aisle.

Since starting his career in 1971 as a Christian recording artist, the father of two children has recorded nine albums with The Word Records. His style is direct, witty and sometimes critical of organized religion and his fans are very loyal.

"I think he's the best of the modern Christian singers," said Steve Chapman, 22, of Arlington. "The others are good, but they don't have the talent that comes so naturally to Ken."

Another man in the audience said, "You have to hear him to realize how good he is. He's very relaxed with an audience . . . . he's very witty."

Medema has been blind since birth and he knows how to put people at ease with his blindness.

"These children are passing out bread and it's up to you to share it among yourselves," he instructed as he stood with his hands on the piano.

Medema's nonstop instructions turned into a song accompanied by what seemed a complex concerto. For the next hour and a half, the audience swayed with his rollicking antics and ballads.

"My music is more controversial than most pop-religious music," admits Medema. "It doesn't say 'Get right with God and everything will be okay.' It asks how can the church talk of love and endorse war, how can the church talk of righteousness and neglect hungry people?"

His straightforward approach to life was enhanced, he says, by the seven years he worked as a musical therapist with teen-agers at a psychiatric hospital in New Jersey. Medema has bachelor's and master's degrees in musical therapy.

"The first song I ever wrote was inspired by a group of about 60 kids I was working with" at the hospital, he recalls. "We were singing 'The Age of Aquarius' and I stopped and said 'Do you think things will ever get better?' One kid said, 'No there ain't nobody to touch my soul.' "

Medema says he was inspired to write a song that says: "Touching is a very hard thing to do/ Seems you can't get to me and I can't get to you/ What are we afraid of/ Why can't we share/ We're never gonna make it/ and why can't we care?"

Medema said in a recent interview that "blindness has given me a preconditioned empathy for people who have been shafted." He continued, "it helped me understand the kids I worked with.

"Some of the most narcissistic kids, the ones that no one could reach, they would help guide me. Even though I didn't need help, I'd act like I couldn't get around and I guess they'd feel sorry for me and they'd help me." He laughs again and adds, "Believe me, I milked that for all it was worth."

Medema discovered the piano at the age of 8. "Oh, my piano teacher, she was wonderful," he says with the same enthusiasm he has for anything relating to music. "She studied at Juilliard and was really concert quality, but she preferred to teach . . . . She learned to read music in Braille just to teach me . . . . She said I had potential. I studied with her until I went to college."

Medema now performs throughout the United States, traveling about four days a week. As a comedian, he keeps his audiences laughing with skits like "the gospel according to Bell Telephone" in which he reenacts Bible stories as if the characters lived in the 1980s and received messages from God via surprise telephone calls.

He was raised in the Dutch Reform Church and says his religious upbringing was very strict. "I wasn't allowed to do a lot of normal things . . . . I couldn't go to movies . . . . Everything when I was growing up was 'you can' or 'you cannot' do this."

By the time he went to college, Medema says he had to "absolutely leave the church completely" in protest. Medema credits his wife, the daughter of a minister, with bringing him back to the church.

"I've known Ken since 1974," says the Rev. Mary Lewis, minister of Southeast Johenning Baptist Center. "He's worked for years to bring blacks and whites together by talking about hunger. I told my friend she'd see all kinds of people at this concert. He relates to blacks, whites, old and young equally."

Lewis pauses for a moment, then adds, "He reflects in music what a lot of people feel in their hearts."

Later that night, Medema's music ended as he walked back down the aisle and sang, "We will not rest till all the world shall feast. There's still much to do, blind eyes to open and deaf ears to hear."