"And I say unto you, Every one who shall confess me before men, him shall the Son of man also confess before the angels of God: but he that denieth me in the presence of men shall be denied in the presence of the angels of God." (ASV)
Have you ever known a "closet Christian"? There are more of them out there than you know -- people who love and worship God in private, but never speak His name or profess their faith in public. Many are afraid of what their friends will think, afraid of looking foolish, or simply afraid their faith may be questioned if it is revealed. This is not the type of relationship God wants from us.
Imagine yourself in a relationship with that perfect guy or gal. Things are great when you're together. They bring you gifts and shower you with affection. But you never go out to the movies or a restaurant together. You never get to meet their friends or family. You're never seen in public together. No matter how much you love the other person, this charade would eventually get old, and you'd demand that they stop trying to hide your relationship. Yet this is the same way many people treat the God who created them and who loves them very much!
God doesn't want to be confined to Sunday mornings or quiet times when we're alone. He wants to be first and foremost in our lives. "For our God is a consuming fire." (Hebrews 12:29 ASV) If we're truly on fire for Him, we won't be able to hide it. We won't even want to! We'll want to share His love with everyone we encounter. We'll gladly let the world know that we belong to Him.