Evangelist Billy Graham has said that when addressing couples who are living together but are unmarried, it's important to remind them that they run the risk of "great unhappiness" in the future.

In a Q&A published Thursday by the Billy Graham Evangelistic Association, Graham was asked: "My nephew just moved in with his girlfriend, and when I told him I thought it was morally wrong, he just laughed and said no one believes that anymore. Anyway, he said, he's not interested in God, because the only thing that counts is being happy. What can I say to him?"

The 98-year-old evangelist responded by saying that first of all, it may be difficult to say anything that will change the minds of the couple living together.

"From what you say, he's interested only in what's happening in the present moment, and he doesn't want anyone to interfere with what he's doing-including God," Graham said.

However, he advised talking about the future: "First, remind him that although he thinks he's found happiness, he actually is running the risk of great unhappiness in the future," he explained. "Relationships like this always lack one thing: stability. The reason is because-unlike marriage-they lack true commitment, and can unravel at any moment. What happens if one of them gets bored, or upset, or finds someone more attractive?"

It's also important to remind couples of their need for God's guidance and wisdom, Graham said.

"A life lived only for self is empty and insecure-but God loves us, and He knows what is best for us," he said. "Pray for your nephew, that he will face his need for God's forgiveness and new life. Pray too that you will be an example to him of Christ's love-a love that far exceeds the pleasures of the moment."

According to statistics, cohabitation has increased by nearly 900 percent over the last 50 years, with 7.8 million couples living together without walking down the aisle, compared to 2.9 million in 1996.

Unfortunately, research also indicates that couples who cohabit before marriage have a 50 - 80 percent higher divorce rate than those who don't. They also have higher rates of domestic violence and are more likely to be involved in sexual affairs.

In an earlier "My Answers" column, Graham further weighed in on the problem with cohabitation before marriage: "On a practical level, the problem with simply living together is that there's no real commitment, either to each other or to marriage," he explained. "What's to keep your boyfriend from deciding he doesn't want to be tied down, and suddenly casting you aside? Or what's to keep you from leaving after a minor disagreement (as happens in almost any relationship)? The answer is simple: precisely nothing."

He also offered up a reminder that God gave marriage to us for our happiness and mutual help.

"In His eyes it's a solemn commitment to be faithful to each other, no matter what happens. This is why the Bible commands us to avoid sexual relations outside of marriage. Only then can true love flourish, and only then will your relationship grow stronger over the years."