This is the question I answered in my most recent seminary assignment. In a five-page paper, I had to expound on a one-sentence definition of evangelism. No borrowing allowed. It had to be my own definition. Sounds easy, right? It was actually one of the most difficult tasks I’ve had thus far in grad school. This is my single-sentence definition:
Being rooted in the love and grace of the triune God to restore his sin-tarnished creation, evangelism is the activity of God through his church (a) to bear witness to the reality of the Kingdom of God inaugurated by and under the rule of Jesus Christ, (b) to invite men and women into the restored existence of this Kingdom, and (c) to mobilize Spirit-inspired laborers for the further realization of this Kingdom on earth.
I welcome your thoughts and critiques.