Therefore Jesus said again, "I tell you the truth, I am the gate for the sheep... I have come that they may have life, and have it to the full. (John 10:7... 10, NIV)The full passage: John 10:7-10
Have you ever wanted to convince an unbeliever why he/she should be a Christian? The Christian philosopher, Pascal, argued for being a Christian versus an atheist/agnostic. If Christianity is true, then he had much to gain from being a Christian and much to lose by not being one. On the other hand, if Christianity were false, then he had nothing to gain or lose by either being a Christian or not. Thus, he argued it made more sense to be a Christian.
This argument doesn't appeal to the mindset of people today. It appeals too much to the afterlife. Asking an atheist or agnostic this question seems to give the same argument in a more relevant way for the mindset today. If my Christianity were false, does living your life the way you see fit with your atheistic/agnostic beliefs give your life more value or make you more satisfied than me living my life by my Christian beliefs?
This question does more than challenge the atheist and agnostic. It challenges us to live up to our beliefs not only for our own satisfaction, but also to glorify God. If an atheist became your best friend, knew the details of your personal life, and lived with your family, would he/she see a fulfilled life in Christ? It's not a matter of circumstances being good in your life. Anyone can be happy when everything goes his/her way. When adversity comes, will you let it steal your joy? Or, will you trust God, who is in control, and recognize everything cooperating to shape us into His image (Romans 8:28-30)?