Despite major changes in public opinion in recent years, Rev. Franklin Graham, son of perhaps the most famous American preacher of all time, Billy Graham, reiterated his strong opposition to gay marriage and gay adoption today on ABC's "This Week."

As a part of a special Easter week discussion on religion, Graham told ABC News' Martha Raddatz that gays could go to heaven if they repent.

"Maybe gays that are watching want to know, 'Can God forgive me? Or can I go to heaven as a gay person?' Absolutely. But the same for any of us. We have to repent of our sins in turn. A person cannot stay in adultery and be accepted by God. You'll have to repent," said Graham, president of the Billy Graham Evangelistic Association.

"Franklin Graham is a sinner, and I'm no better than a gay person. I'm a sinner," he added. "But I've been forgiven, and I've turned from my sins. For any person that's willing to repent in turn, God will forgive."

ABC News' Cokie Roberts replied: "A lot of gay people feel that they are sinners, but not because they're gay."

In the last decade, public opinion has swung dramatically on key issues pertaining to gay rights, including gay marriage and adoption. An ABC News/Washington Post poll from March found approval for same-sex marriage at an all-time high: 59 percent of total respondents said they approve, including 75 percent of respondents under 30 years old.

While evangelical Christians overall are more likely to disapprove of same-sex marriage, younger evangelicals are nearly split on this issue: 43 percent of evangelicals under 30 years old said they approve of the idea.

The same poll also found that a majority of Americans, 61 percent, also now approve of gay adoption.

"The reason the numbers have changed so fast and so dramatically on this question of gay marriage is because everybody in America now has experience with someone who is gay," Roberts said. "People have come out of the closet and said, 'I am your brother. I am your sister. I am your cousin. I am your friend.' And then they have seen these families raising children and see these loving families."

Ralph Reed, chairman of the Faith and Freedom Coalition, noted that overwhelmingly states still define marriage as being between a man and woman, while voicing his belief that laws should be written based on an "ideal" for families.

"I think that the social science is just simply not in yet on same-sex couples, and I think the law has every right to set an ideal, and the ideal is a mother and father," he said.

Politically, the majority of evangelical leaders - 82 percent - think evangelicals' influence is waning in the U.S., according to a 2011 Pew poll. Simultaneously, church attendance and membership is at record lows in the U.S.

Dr. Russell Moore, president of the Southern Baptist Convention's Ethics and Religious Liberty Commission, said during the discussion that he is not worried about the decline in numbers, saying the current membership reflected a more "authentic" Christianity.

"I think what we're seeing is the collapse of a cultural nominal form of Christianity. There was a time in America where in order to be a good person, to be seen as a good citizen, one had to nominally, at least, be a member of a church," Moore said. "Those days are over.

"We're at a point now where Christianity is able to be authentic," he said. "It offers an opportunity for the church to speak clearly, articulately about what it is that we believe."

As for the issue of evangelical's political influence, Reed contended his organization's lobbying efforts are still going strong.

"We conduct voter registration drives. We pass out voter guides," he said. "They have been writing the obituary of this movement for 30 years."

When asked about the health of his father, Franklin Graham said he is "doing pretty well."

"Ninety-five years of age, and his mind is still sharp," he said of Billy Graham. "And that's what's so amazing."