For a Christian Broadcasting Network program, youd probably expect the number to be biblically based. But, as usual, moneys at the root of it.
CBN was founded in January of 1960 and broadcast its first program October 1, 1961. The network refused commercial advertisements, so by the fall of 1963, CBN conducted its first telethon to raise funds to keep the station alive. Pat Robertson, CBNs founder, told his viewers that a club of 700 contributors, each giving $10 a month, would allow CBN to meet its expenses.
By 1965, the annual CBN telethon had been so successful that Robertson added a new program to the end of his stations broadcast day: The 700 Club, which followed the telethons format of prayer and ministry coupled with telephone response.
Robertson has since used those CBN resources to launch numerous other business ventures including: the Family Channel, designed to distribute The 700 Club, which became International Family Entertainment in 1990; Northstar Entertainment; Broadcast Equities; CBN Travel; American Sales Corporation; International Charter Jet; Kalo-Vita; and the Founders Inn and Conference Center.
Today, the Christian Broadcasting Network, Inc., is a multimillion-dollar organization that makes money on everything from hawking higher education to digging diamonds in Zaire.
According to Robertson, his close relationship with God has given him the insiders scoop on successfully using what he calls Gods marvelous system of money management.
https://www.straightdope.com/21342523/why-is-the-700-club-called-that
On the plus side, it did inspire this masterpiece...