Prove it. If you witness to enough people long enough in this life you will hear these words eventually, prove it, prove to me that this God, this Jesus Christ you serve is real. The real question though is can you answer them, can you prove to them that this invisible God, this One you say is beside you and inside of you at the same time, all the time, is actually real, that He exists and is at work in the lives of men.
Some will try to accomplish this task with the Word of God, they will quote Scriptures, read the verses that pertain to the questions, but to many of the lost these are just quaint stories, fables passed down thru the ages to amuse small children and give false hope to the weak minded, to them they are no more true than the best-selling fiction book of the day, written to keep the lowly masses in subjection while the strong continue to rule the planet, made for lovers and dreamers who cannot stand on their own two feet and get about the business of life.
Some will attempt to sway these lost souls with historical documentation, just as believable to most of them as the Holy fables book that you have been trying to get them to believe. History is being rewritten as we speak, those who desire to control the present can very easily disrupt the past, every nation has done it to try to continue fealty to their flag, to their cause. The history of this planet is only as reliable as those who hold power today, what suits their cause is all that matters, the past is easily modified with words spoken or written, and when the young are taught a different view than the old, as time wears on, the old will almost always be thrown out for the new. The history of the Bible, no matter how much secular history corroborates it, is rarely going to affect the thoughts of the lost.
You could of course give them your testimony, sometimes they listen, sometimes not, after all, what has been accomplished in your life has been accomplished by others who do not serve this Risen Savior you keep trying to bring to their attention. Many alcoholics have stopped drinking on their own, many drunks, wife beaters, evil men have changed their lives, have made a 180 degree turn without calling on God for assistance. Even the miracles that have occurred in your life are many times explained away quite easily, did not Jannes and Jambres turn their rods into snakes, (Exo. 7:12) were there not some who were casting out demons that were not part of Jesus’ followers? (Mark 9:38) Many good men have accomplished many great deeds without bringing God into the equation. All these and more have I heard, all these and more will you hear, and all they will hear is platitudes, reasonings, written documentations and oral exercises, they will not hear or understand that, “For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.” (Romans 1:17) “No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.” (John 6:44)
They are in your presence for a reason, nothing happens to the servants of Christ by accident, they have listened, they have questioned, and now they want answers, and you are expected to give them these answers. They are willing to listen, but they do not want platitudes from some old religious book, they do not want a history lesson, and although they may be happy for you, your reasons of some invisible sky daddy are not enough to bring them to the knowledge of Christ and the salvation that awaits all who will call upon Him. I have dealt with these individuals before, and they are one of the few groups of people on this planet that can bring me to a level of frustration I do not care to be at, I have learned my lesson, and so now each of them receive the same response from me, “Since I am unable to prove the existence of Christ to you, why don’t you go home and ask Him to prove Himself to you, stop asking me, and go ask Almighty God to prove Himself.”
I have received some very interesting looks the next day, very interesting indeed, as if I was some sort of magic man, a person with special abilities that others do not have. What we have as born-again believers is a personal relationship with Christ, corporeal when we are in assembly together, worshipping His name, glorifying Him in the highest, but in the most extreme essence that I can put into words, the servants of Jesus Christ have a personal relationship with Almighty God that the lost will never understand. That is how you can reach these individuals, that is how you can bring them to the cross and allow them to face the truth for themselves, you let God do it.
Many have come to Christ in this manner, especially in a day when some who profess His name are not living as the Lord would have them to, Sunday morning only Christians, worldly the remainder of the week. When God makes it personal, people listen, people are not always convicted and fall to their face, becoming our brothers and sisters in Christ, but I can guarantee you they listen. We do not save anyone, those that are saved have been called by God to the knowledge of the truth of His Son, (1 Cor. 1:9) we are simply messengers, but sometimes the messenger needs to send the one they have been sent to directly to the one that has sent them. They will listen then my friends, what they do after that is completely up to them, but again, I can guarantee you one thing, all those foolish questions from them from that day forward will come to an abrupt end.
“For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.” (1 Cor. 1:18)