Don't forget to use the K.N.O.W. acronym when witnessing to unbelievers.

Knowledge claims or morals where do they coming without the Christian God

Not on my worldview remind them they cannot rob from the Christian worldview to hold up their inconsistent worldview

Open up their worldview to show the inconsistencies and arbitrariness

Weave it back to the Gospel

Using this acronym allows you to ask a lot of questions. Gives you the opportunity to review what they believe to show their inconsistencies. While weaving it back to the truth that will set them free from their sin. (John 8:32) Hope this helps you to go out and witness with boldness.