My son shared this video with me on YT of Dr. Hugh Ross, an astrophysicist, describing a "chance" encounter on an airplane with an atheist quantum physicist who began asking questions. It's 1:30 long but the first 30-40 minutes covers the encounter and the remainder is Q&A from the audience. I think it's a great video on several levels. If you have a half hour, I highly recommend watching.
I didn’t realize Ross was still around. He’s got to be getting up there. He is in some ways a tragic figure.
The thing I liked most about this video are the anecdotes he related about the way God guides witnessing and brings 'seekers' into the conversational sphere of 'believers' in order that 'believers' can give account of the hope that is in them. Witnessing is definitely a ministry guided and orchestrated by The Holy Spirit. I have experienced this many times myself. On the strength of his testimony I have now bought his book.