Body Life is the entire body participating in the lives of each of its members. It is comes directly from (verses). Starting in the late 1960's PBC began having regular times where the whole congregation would gather and individual members would speak about what was going on in their life. It was a bit like the "sharing" time commonly found in small groups today but it involved the whole church. Ray wrote an entire book on the subject entitled, of course, Body Life.
Ray fully embraced personal, relational discipleship. On his frequent speaking trips, he always took a handful of young men with him to participate in his ministry. He also met with these men regularly to instruct and encourage them in an informal setting. It is a testament to his work in this area that many of these young men went on to be pastors in a variety of settings.
Expository preaching focuses first on discovering and interpreting what the Bible actually says and then looking to apply that in the current context of life. This is the opposite of "topical preaching" which seeks first to address a topic in the current context of life and then looking for scriptural references to support the topic.
The clergy/laity distinction that is quite common today is not found in the New Testament. The primary means of God working in the world is through each individual Christian. God has given spiritual gifts to everyone who believes in Him and He means them to actively use those gifts for the advancement of His kingdom. Ray realized that his primary ministry was to teach Christians so that they were better equipped to do their own ministry.
This was perhaps the central theme of Ray's, summarized in his phrase: "Nothing coming from us, everything coming from God." This is rooted in Paul's second letter to the Corinthians in which he says "Not that we are adequate in ourselves to consider anything as {coming} from ourselves, but our adequacy is from God, who also made us adequate {as} servants of a new covenant, not of the letter but of the Spirit; for the letter kills, but the Spirit gives life." (2 Cor. 3:5-6) The new covenant means not trying to do things for God but just showing up and letting God do things through us. Ray wrote a whole book on this theme called Authentic Christianity.
Rather than a hierarchical leadership/management model patterned after today's businesses, Ray taught that everyone reports directly to Jesus Christ. God did outline the role of elders but they were to be His under-shepherds, carefully looking out for the health of the flock and chiefly characterized by serving them. Jesus commands this when he says "And He said to them, "The kings of the Gentiles lord it over them; and those who have authority over them are called 'Benefactors.' But {it is} not this way with you, but the one who is the greatest among you must become like the youngest, and the leader like the servant." (Luke 22:25-26)
Ray never wanted to be the "senior" pastor as this went against his non-hierarchical leadership principles. Each local church body should have a plurality of men with strong pastor-teacher gifts that teach and encourage the body. This prevents a church becoming the church of the senior pastor as opposed to the church of Jesus Christ.
In the context of discussing the gifts of the Spirit, Paul mentions: "But to each one is given the manifestation of the Spirit for the common good." (1 Cor. 12:7) Every believer has been given particular spiritual gifts that he is to exercise for the benefit of the entire body.