In 1975, two Christian leaders, Dr. Bill Bright and Loren Cunningham, got together to give each other a message from God. To their amazement, each had the same message, independently given to them by God, to give to the other.
Bill Bright was the founder of the world’s largest ministry, Campus Crusade for Christ, a worldwide ministry with 26,000 full-time employees and missionaries in 191 countries. Loren Cunningham was the founder of Youth With A Mission (YWAM), a ministry with 20,000 full-time staff of more than 150 nationalities. Both of these individuals brought the message of God's love to millions around the world.
However, God had shown both of them that many areas of modern culture still needed to be transformed by the knowledge of God's love. The Lord showed them seven major areas of society, or “mountains” as they called them, which needed righteous people to influence them, thereby influencing untold millions who were engaged in those seven mountains of society. About a month later, Francis Schaeffer, leader of L’Abri Fellowship, heard the same thing from God.
These seven mountains are business, government, media, arts and entertainment, education, family and religion. God was showing them, in 1975, that this was the way to make the biggest difference in this world. God wanted these men to equip people to go into these seven mountains of culture and to make positive change: to begin reconciling culture back to God's way of love.
Reference: "Origin of 7 Mountains Concept and 7MKI"