What evangelism really is
I will attempt to define evangelism and bring out its essential nature of from 1 Thessalonians 2 and 1 Corinthians 9:15-27
1 Thessalonians 2.
Evangelism, the heralding of good news, is not easy. For in evangelism the church attacks the strongholds of Satan, who hold the whole world in deception. True evangelism is often seen in Christians being mocked and despitefully mistreated, v.2.
But God honours true evangelism and is often pleased to make the seed grow and bear fruit. The Father is the Lord of the harvest (Luke 11); he grants or withholds success; Christ is the builder of his church (Matthew 16); the Holy Spirit is the divine Energizer and Commissioner (Acts 13:1ff). Where the triune God is honoured and his doctrine is maintained, preachers will (generally) not labour in vain (v.1).
True evangelism explores the question of motives: why does such and such a person preach the gospel? Is it for his fame, his advancement on the ecclesiological ladder, his financial gain? Paul could vouch for his sincerity and right motives (v.3). He considers himself a servant, or rather, a steward entrusted with a commission (v.4). He knows whom he is to please. True evangelism looks to God primarily: it is for His Name's sake (Romans 1:5; 3 John 7) that evangelists go out, v.4.
The evangelist is involved: "you were dear to us." He is a lover of souls. He does not abuse his authority. He would prefer to preach without cost: Paul sometimes worked as a tentmaker to pay expenses.
At all costs, the evangelist must remember that he is a model of the gospel: the gospel has changed him. His example speaks, perhaps more than his words.
1 Corinthians 9:15-27.
An evangelist's ministry is not a job that can be chosen at will. Though every Christian has the responsibility to share the gospel and give a reason for the hope within him, as God provides the opportunity, the evangelist has a necessity laid upon him. It is his burden, an awesome responsibility that he cannot escape or avoid. v.16. Even if God finds his evangelists unwilling at first (Moses, Jeremiah, Amos), he makes them willing and promises them his presence and enablement.
True evangelism is adaptable and flexible, not rigid. Christ spoke to the Samaritan woman very differently than how he approached the learned Nicodemus. The same gospel was given; the approach was tailored to the needs and capacities of his hearers. That is why Paul became a servant to all: to the Jew he became a Jew...to win them to Christ. This is not compromising the content of the message, far from it. It is adaptability.
Paul spoke to the Jews, reasoning with them from the Old Testament, with which they were familiar. To the Athenian philosophers, he never quoted the OT, but his message is nevertheless biblical and the same Christ is preached.