from http://www.unlessthelordmagazine.com/articles/Church%20w%20Family%20Only.htm
Reasons for a Local Church
A key part of the evangelism efforts of the apostles was the formation of local assemblies of believers. The work of evangelism was not complete when people came to Christ, nor when they had sat under an apostle's teaching for 6 months. The job was not done until there was a functioning local body of believers that could perpetuate itself. This assembly served the purposes of: maintaining unity, maintaining correct doctrine, evangelizing unbelievers, discipling new believers, and correcting those who strayed. It also offered a family of believers from which to receive love, encouragement and practical assistance. The church was to be the main vehicle for Christian growth and for serving God together.
A key part of the evangelism efforts of the apostles was the formation of local assemblies of believers. The work of evangelism was not complete when people came to Christ, nor when they had sat under an apostle's teaching for 6 months. The job was not done until there was a functioning local body of believers that could perpetuate itself. This assembly served the purposes of: maintaining unity, maintaining correct doctrine, evangelizing unbelievers, discipling new believers, and correcting those who strayed. It also offered a family of believers from which to receive love, encouragement and practical assistance. The church was to be the main vehicle for Christian growth and for serving God together.