When Twin City Baptist Church launches its 40 Days of Purpose campaign on Sept. 24, it will join a global network of thousands of churches from 60 denominations that have responded to stories of spiritual renewal and growth. At the center of the campaign is a book, “The Purpose-Driven Life,” by the Rev. Rick Warren, a Lake Forest, Calif., Baptist pastor. It has sold 16 million copies since 2002. The 40-day campaign emphasizes “the truths about God’s five purposes for people – worship, fellowship, discipleship, ministry and evangelism” – through an all-church seminar Sept. 24, a weekly message by the pastor, personal or family devotionals, a weekly memory verse, a weekly small group or Sunday school lesson, a daily e-mail of encouragement. “This will allow for the truths to sink deeper into hearts, which is essential for any permanent life change,” said the Rev. Gary Turgeon, pastor of Twin City. A cookout begins the campaign at 5:30 p.m. Saturday, Sept. 24, at the church, 559 N. Main St.