Heralding the Gospel in the Public Sphere
In the New Testament, God sends the church out to proclaim the gospel in the act of public witness. One of the words used most frequently for the people of God announcing the gospel is kerusso, which is normally translated: 'to preach' in English Bibles. However, it is not related to the idea of preparing and delivering sermons in the context of Christian worship. It’s true meaning was 'to herald.' It had to do with the task of one sent out to make a public announcement on behalf of one in authority, in this case of the church - the risen and ascend Christ.
In those times, heralds spoke on behalf of kings, princes, military leaders, magistrates or civil authorities. They personally and publicly conveyed the message of the one in authority to the people, unchanged and with clarity and solemnity. Thus, it was a word used commonly for those representing a public authority figure. Such heralding underscored the character of the herald as one representing a person of authority. The gravity, dignity and authority of his proclamation came "with the suggestion of formality, gravity and an authority which must be listened to and obeyed" (Thayer's New Testament Greek Lexicon). Thus, the church's witness is serious business, and it is located squarely within the public sphere. It is there that the gospel must be heralded rather than the confines of a church building, which is often the case today.