Evangelist Billy Graham has encountered many people in his lifetime, including once-fervent Christians who somehow found themselves losing their faith. He has observed that people turn their backs on their faith for several reasons.

"Often, for example, they simply get too busy or preoccupied with other things. Or they get in with a group of people who never think about God, and they give in to the pressure of the crowd. Still others conclude that faith simply has no place in an intelligent adult's life," Graham writes for The Kansas City Star.

But no matter what their excuse might be, Graham says there are only two reasons why people turn away from their childhood faith.

The first reason is that their faith is too shallow and lacked any real commitment. "Children may not understand everything — but they can understand that God loves them, and Jesus Christ came into the world to offer them the gift of eternal life. Moreover, they can understand that they need to commit their lives to Jesus by inviting him to come into their lives. Faith and commitment go hand in hand," he says.

The second reason why people reject their childhood faith is that they fail to understand that their faith needs to grow. Graham used Jesus' parable of the seed to state his case. "A plant with no roots eventually withers and dies — and the same is true of faith," he says.

Jesus said in Luke 8:13: "They believe for a while, but in the time of testing they fall away."

Graham encourages Christians to pray for people who have lost their faith to rekindle their love for Jesus and rush back to Him. He also urges people to pray for the youth of today—that they grow up developing a real commitment to Jesus and that they will grow stronger as they read the Bible, spend time in prayer, and fellowship with other believers.