The word "unknown" has been added to the text . . . as shown by "italics". Why is it that MY understanding is not straight but YOURS is?
"Since both a Christian church and individual Christians are likened to a building or temple in which God or the Holy Spirit dwells, the erection of which temple will not be completely finished till the return of Christ from heaven, those who, by action, instruction, exhortation, comfort, promote the Christian wisdom of others and help them to live a correspondent life are regarded as taking part in the erection of that building and hence are said to (dropping the figure) to promote growth in Christian wisdom, affection, grace, virtue, holiness, blessedness . . . passive - to grow in wisdom, piety, etc." - Thayer's Greek-English Lexicon of the New Testament
Vine's Concise Dictionary of the Bible - oikodome - edify (noun) denotes the act of building (oikos - "a home", and demo "to build"); this is used only figuratively in the NT, in the sense of edification, the promotion of spiritual growth (lit., "the things of building up"), [Romans 14:19; 15:2; 1 Cor. 14:3,5,12,26, e.g.] . . . or figurative, of the future body of the believer [2 Cor. 5:1], or of a local church, [1 Cor. 3:9, or the whole church, the body of Christ [Eph. 2:21]
Bullinger's Critical Lexicon and Concordance to the English and Greek New Testament - to build a house, and then generally to build, construct. Metaphorically to build up, establish.
For the common good [for that which is profitable] - to the church for edification, building up the body of Christ, giving strength and growth by encouragement, exhortation; . . . for the common good [for that which is profitable] to the individual, building up spiritually giving strength and growth to the individual so that they in turn can strengthen the body by encouragement and exhortation.