There are many reasons why we must evangelize. John Calvin offers the following:
1. God commands us to do so. “We should remember that the gospel is preached not only by the command of Christ but at his urging and leading.”
2. We want to glorify God. True Christians yearn to extend God’s truth everywhere so that “God may be glorified.”
3. We want to please God. Calvin writes, “It is a sacrifice well-pleasing to God to advance the spread of the gospel.”
4. We have a duty to God. “It is very just that we should labor … to further the progress of the gospel,” Calvin says. He adds, “It is our duty to proclaim the goodness of God to every nation.”
5. We have a duty to our fellow sinners. Our compassion should be intensified by knowing that “God cannot be sincerely called upon by others than those to whom, through the preaching of the gospel, his kindness and gentle dealings have become known.”
6. We are grateful to God. We owe it to God to strive for the salvation of others; if we do not, we are behaving in a contradictory manner. Calvin says, “Nothing could be more inconsistent concerning the nature of faith than that deadness which would lead a man to disregard his brethren, and to keep the light of knowledge … in his own breast.”
This excerpt is taken from Living for God’s Glory: An Introduction to Calvinism by Joel Beeke.