Update: I asked Steve Wilkins what his thoughts were on Lewis’ quote, since his book on Frriendship and Hospitality was so helpful to our congregation. He wrote:
If we are built up in conformity to Jesus through the ministry of the members of the body (Eph. 4) then we may say that salvation is ministered to us from the Father, through the work of the Son, by the Spirit as He works in and through our brothers and sisters (our friends). The fact is I can’t be saved apart from the body of Jesus — and that’s the same as saying I can’t be saved apart from my friends. If that’s so, then friends are a necessity, not a luxury; they are central to life not auxiliary to it.