The Antioch church is glad for the letter's encouraging, indeed comforting, message (compare 9:31). Where there had been terror (v. 24) there is now joy. And rightly so, for the Gentile converts know where they stand with reference to Judaism and to Jewish Christian believers. There is no circumcision requirement, but full acceptance. They have received guidance on respect for Jewish Christian scruples so full table fellowship can be enjoyed. When gospel truth and Christian love are promoted, there is every reason for joy among all those who would enter and live in such an attractive, wholesome fellowship.
Being prophets, Judas and Silas are supernaturally gifted, like their Old Testament counterparts, to apply the word of God to the personal and corporate circumstances of God's people (compare 1 Cor 14:3, 31). They enter into a lengthy ministry of pastoral exhortation, to encourage and strengthen the brothers. They repair the Judaizers' damage (Acts 15:24) and enable the saints, in matters of the gospel, to re-lay a firm foundation (Bauer, Gingrich and Danker 1979:768; compare 14:22).
Ceremoniously, the prophet-envoys later take their leave of the Antioch church with the blessing of peace to return to those who had sent them. And the church with renewed vigor engages in outreach. Paul, Barnabas and many others remain to teach and "evangelize the word of the Lord." As living organisms are able to rejuvenate themselves when damaged, so the Spirit of God can and will repair the wreckage of hurt feelings, strained relations and wrong thinking brought to the body of Christ by the infiltration of false teaching. What it takes is a church willing to take the time, expend the human resources and make the effort to do the repair work.