The Biblical concept of “preaching” is best ascertained from an examination of the sense of the original Hebrew and Greek terms. The Greek ke·rysʹso, which is commonly rendered “preach,” means, basically, ‘make proclamation as a herald, to be a herald, officiate as herald, proclaim (as conqueror).’ The related noun is keʹryx and means...
The Biblical concept of “preaching” is best ascertained from an examination of the sense of the original Hebrew and Greek terms. The Greek ke·rysʹso, which is commonly rendered “preach,” means, basically, ‘make proclamation as a herald, to be a herald, officiate as herald, proclaim (as conqueror).’ The related noun is keʹryx and means ‘herald, public messenger, envoy, crier (who made proclamation and kept order in assemblies, etc.).’ Another related noun is keʹryg·ma, which means ‘that which is cried by a herald, proclamation, announcement (of victory in games), mandate, summons.’ (A Greek-English Lexicon, by H. Liddell and R. Scott, revised by H. Jones, Oxford, 1968, p. 949) Ke·rysʹso thus does not convey the thought of the delivery of a sermon to a closed group of disciples but, rather, of an open, public proclamation. This is illustrated by its use to describe the “strong angel proclaiming [ke·rysʹson·ta] with a loud voice: ‘Who is worthy to open the scroll and loose its seals?’”—Re 5:2; compare also Mt 10:27.
The word eu·ag·ge·liʹzo·mai means “declare good news.” (Mt 11:5) Related words are di·ag·gelʹlo, “declare abroad; give notice” (Lu 9:60; Ac 21:26; Ro 9:17) and ka·tag·gelʹlo, “publish; talk about; proclaim; publicize.” (Ac 13:5; Ro 1:8; 1Co 11:26; Col 1:28) The principal difference between ke·rysʹso and eu·ag·ge·liʹzo·mai is that the former stresses the manner of the proclamation, that it is a public, authorized pronouncement, and the latter stresses the content thereof, the declaring or bringing of the eu·ag·geʹli·on, the good news or gospel.
The Hebrew Scriptures also pointed forward to the preaching work that would be done by Christ Jesus and the Christian congregation. Jesus quoted Isaiah 61:1, 2 as foretelling his divine commission and his authorization to preach. (Lu 4:16-21) In fulfillment of Psalm 40:9 (the preceding verses being applied to Jesus by the apostle Paul at Heb 10:5-10), Jesus “told the good news [form of ba·sarʹ] of righteousness in the big congregation.” The apostle Paul quoted Isaiah 52:7 (concerning the messenger bringing the news of Zion’s release from its captive state) and related it to the public preaching work of Christians.—Ro 10:11-15.
The theme of Jesus’ preaching was: ‘Repent, for the kingdom of the heavens has drawn near.’ (Mt 4:17) Like an official herald, he was alerting his listeners to his Sovereign God’s activity, to a time of opportunity and decision. (Mr 1:14, 15) As foretold by Isaiah, not only did he bring good news and comfort for the meek, brokenhearted, and mourning ones, as well as proclaim release to captives, but he also declared “the day of vengeance on the part of our God.” (Isa 61:2) He boldly announced God’s purposes, decrees, appointments, and judgments before rulers and people.
After Jesus' death, and particularly from Pentecost of 33 C.E. onward, Jesus’ disciples carried on the preaching work, first among the Jews and eventually to all the nations. Anointed by holy spirit, they recognized and repeatedly informed their listeners that they were authorized heralds (Ac 2:14-18; 10:40-42; 13:47; 14:3; compare Ro 10:15), even as Jesus had stressed that he was ‘sent by God’ (Lu 9:48; Joh 5:36, 37; 6:38; 8:18, 26, 42), who gave him “a commandment as to what to tell and what to speak.” (Joh 12:49) Therefore, when ordered to cease their preaching, the disciples’ reply was: “Whether it is righteous in the sight of God to listen to you rather than to God, judge for yourselves. But as for us, we cannot stop speaking about the things we have seen and heard.” “We must obey God as ruler rather than men.” (Ac 4:19, 20; 5:29, 32, 42) This preaching activity was an essential part of their worship, a means of praising God, a requisite to the gaining of salvation. (Ro 10:9, 10; 1Co 9:16; Heb 13:15; compare Lu 12:8.) As such, it was to be shared in by all disciples, men and women, down till “the conclusion of the system of things.”—Mt 28:18-20; Lu 24:46-49; Ac 2:17; compare Ac 18:26; 21:9; Ro 16:3.
Their preaching was not performed simply as a duty, nor did their heralding consist merely of speaking out a message in a formal way. It sprang from heartfelt faith and was done with the desire to honor God and with the loving hope of bringing salvation to others. (Ro 10:9-14; 1Co 9:27; 2Co 4:13) Therefore the preachers were willing to be treated as foolish by the worldly wise or be persecuted as heretics by the Jews. (1Co 1:21-24; Ga 5:11) For this reason, too, their preaching was accompanied by the use of reasoning and persuasion to help the hearers to believe and exercise faith. (Ac 17:2; 28:23; 1Co 15:11) Paul speaks of himself as being appointed “a preacher and apostle and teacher.” (2Ti 1:11) These Christians were not salaried heralds but were dedicated worshipers giving of themselves, giving their time and their strength to the preaching activity.—1Th 2:9.
Jesus went right to the people with the Kingdom message, teaching them publicly and in their homes. (Mt 5:1; 9:10, 28, 35) When he sent out his early disciples to preach, he directed them: “Into whatever city or village you enter, search out who in it is deserving.” (Mt 10:7, 11-14) Such ‘searching out’ would reasonably include going to the people’s homes, where “deserving” persons would heed the message and the disciples would find lodging for the night.—Lu 9:1-6.
On a later occasion Jesus “designated seventy others and sent them forth by twos in advance of him into every city and place to which he himself was going to come.” These were not just to preach in public places but were also to contact people at their homes. Jesus instructed them: “Wherever you enter into a house say first, ‘May this house have peace.’”—Lu 10:1-7
Matt 24:14 says to preach the good news of Gods Kingdom preached in all the inhabited earth for a witness to all the nations, and then the end will come.
This is what the Jehovah's Witnesses are doing, they are the "only ones" that are doing this, we are preaching in over 900 languages and in over 235 countries! No other faith(religion) is doing this!