Mother Teresa, the Roman Catholic nun and winner of the Nobel Peace Prize for her work on behalf of the poor and dying, called abortion "a terrible evil" yesterday and suggested at an antiabortion convention here that it has created an atmosphere for killing and violence in the world.

"If a mother can kill, can murder, her own child, what is left for others to do?" the 74-year-old nun, who tends the sick and dying in the slums of Calcutta, said during an address to about 1,500 persons attending a National Right to Life convention at the Hyatt Regency hotel.

The tiny, stooped founder of the Missionaries of Charity said unborn children are created "in the beautiful image of God" and she called on her supporters to "help the mothers" to want their children.

"And if they don't want them, tell them Mother Teresa and her sisters want them," she said.

Wearing sandals and a simple white sari with blue trim, Mother Teresa stood on a box to reach the microphones during her address and was given a two-minute standing ovation. After her speech, several women holding babies were invited up to the stage, where the infants were cradled and kissed by the nun -- and by some antiabortion lawmakers.

On Thursday, President Reagan awarded Mother Teresa the Medal of Freedom, and yesterday her Washington visit drew large and awe-struck crowds wherever she went.

"This is a big thrill," said one man, who was among a predominantly Catholic group invited to an afternoon reception for Mother Teresa in Anacostia, where she and Archbishop James A. Hickey helped dedicate a recently opened home for unwed mothers.

The Mary House, which also serves as a soup kitchen six days a week, is operated by the Missionaries of Charity in Washington and is the second home for unwed mothers the order has opened in the United States. It will shelter 12 women.

At a news conference prior to another speech she gave yesterday at the National Shrine of the Immaculate Conception, Mother Teresa said the order now serves the poor, sick and dying in 80 countries and operates nearly 400 houses or convents.

Mother Teresa, a conservative in matters of church doctrine, said she was called by God to serve the poor. Besides her antiabortion stand, she repeated her opposition to women becoming priests and said a woman, instead, "can be a mother, she can be a faithful wife."

In response to a question, Mother Teresa expressed reservations about modern nuns who forgo communal living and traditional nun's habit and become very busy as social workers "doing this and doing that . . . very often, obedience goes."

But she said apartment living or modern dress would be fine if permitted in the constitution of the congregation.

Asked about the current Festival of India being held in Washington, Mother Teresa criticized the display of wealth for a country that is so poor.

" [There's] so much expense for this when we have many, many people who have nothing," she said.

She also said she "looks at all the things here, I feel very angry inside. I see the waste, and I think of the poor."

In one of several personal stories of "God's miracles" or of selflessness shown by others, Mother Teresa recalled how a child from the Calcutta slums had taken a piece of chocolate from his hands and given it to her to feed the hungry when he learned she was going to visit famine-sufferers in Ethiopia.