The Lord of the universe is a talking God, a God who communicates with humankind. As such there are many ways in which He has spoken and many reasons for His speech. At the center of His intentions, however, is the promulgation of the message of grace, the gospel.
This good news is not to be hidden, but told far and wide. The God who speaks has called His people to spread His Word to a lost and confused world. This means that evangelism is of paramount importance in the life of Christians.
Since this is so, believers are to work diligently to promote the name of the Savior, Jesus Christ. Of course this entails many things, from increasing our knowledge of the Scriptures to understanding the culture in which we live. To that end this portion of Truth & Things is intended to inform, promote, and motivate the evangelistic enterprise.
Clearly, a new Christian should witness for Christ as opportunity presents itself, irrespective of the amount of training acquired. But it does not follow that a maturing Christian, five, ten, or twenty years old in the Lord, should still be unskilled in reasoning on behalf of the gospel.
I think we must attack wherever we meet it the nonsensical idea that mutually exclusive propositions about God can both be true.
Success in witnessing is simply communicating Christ in the power of the Holy Spirit and leaving the results to God. Similarly, effectiveness in apologetics is presenting cogent and persuasive arguments for the Gospel in the power of the Holy Spirit, and leaving the results to God.
William Lane Craig
Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit, teaching them to observe all that I commanded you; and lo, I am with you always, even to the end of the age.
But you shall receive power when the Holy Spirit has come upon you; and you shall be my witnesses both in Jerusalem, and in all Judea and Samaria, and even to the remotest part of the earth.
For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek.
The duty of Christian witness involves reasoning, as the descriptions of Paulís missionary activity show. Faith is not created by reasoning, but neither is it created without it. There is more involved in witness to Christ than throwing pre-arranged clumps of texts at unbelieving heads; the meaning and application of the gospel must be explained to men and women in terms of their actual situation. This requires hard thinking.
J. I. Packer