The Bible points to vast difference that unbelievers and believers have. How then can we witness to unbelievers? If there are so many differences, how can we witness to them? Is it possible to have some point of a contact with someone who is of a different faith, or perhaps no faith at all? The answer is yes. God created all things and everything must serve Him. Christians have been brought out of darkness into God’s marvelous light. There is no neutral common ground between the believer and unbeliever. (See this post for more on neutrality). However, there is one thing that all men, believer or unbeliever, have in common – they were created by God. As discussed in Romans 1, unbelievers suppress their knowledge of God in unrighteousness. Greg Bahnsen explains these things in the book, Always Ready.
This [God's ownership and governing of all things] precludes the possibility of any neutral ground between the believer and unbeliever, but it assures us that there is abundant common ground (metaphysically speaking) between them, since all men are God’s creatures and live in God’s world.
As God’s creature, created in God’s image, and living in an environment which constantly brings the revelation of God to bear upon him, the unbeliever is always accessible to the gospel. The believer always has a point of contact with the unbeliever: (1) his being the image of God, and (2) the suppressed truth deep inside him. 
While the common ground is not neutral, it does exist. We must remember that it is God’s ground! We cannot reach out to unbelievers on their terms, or even pretended neutral terms, (which is impossible). Christians must point unbelievers to the Creator and Savior, who alone can remove the suppression of the truth by His grace. Using the tools of apologetics given in the Bible, we can show the unbeliever that only the Christian faith can account for laws of logic, the uniformity of nature, and moral absolutes. The unbelieving worldview cannot and in fact borrows from the Christian worldview to explain these things, demonstrating that there is a knowledge of God within unbelievers. May God give us the wisdom and grace to carry out our task faithfully.
 Bahnsen, Greg, Always Ready: Directions for Defending the Faith, Nacogdoches: Covenant Media Foundation, p. 52.
This post originally appeared at http://takingeverythoughtcaptive.com/2010/12/14/point-of-contact/