In Mark 8:38 Jesus says, "If anyone is ashamed of me and my words in this adulterous and sinful generation, the Son of Man will be ashamed of him when he comes in his Father's glory with the holy angels." Now that's a verse completely removed from its context. It has a very different meaning when you read the rest of the passage.
The disciples have testified that Jesus is the Christ. He begins to teach them about his suffering and death, Peter objects and Jesus tells him to get behind him, Satan. Wow! In one breath Peter gets it, Jesus is the Christ, and in the next breath he shows his complete misunderstanding of everything. This launches Jesus into a little rant about what it means to follow him. Deny yourself. Pick up a cross. Lose your life for Jesus. Then he says if you are ashamed of him here he'll not know you in glory.
It's a little clearer now. Jesus wasn't talking about simple little bumper stickers, forwards, copy/paste, t-shirts, mottos, etc. He wasn't talking about anything in our modern "buy this if you love Jesus" corrupted world. Jesus was talking about the way you live every day. He was talking about putting following him before your own comforts, desires and greed. He was talking about true discipleship; the modeling of one's every move after the one being followed.
Jesus was homeless, spent time with outcasts, loved the poor, healed the sick, stood up for the rejects of his world. He was there for the adulterer, prostitute, tax collector, blind, lame, beggars, children and women. Jesus came in power and strength but not the way anyone expected...not the way we like to expect today. Following Jesus isn't about passing along a vague threat; it is about passing along mercy, charity and justice. Following Jesus isn't about showy prayers and ostentatious acts of pretentious faith. It isn't about judging, excluding and looking down at others. It is about prayers lifted from the heart in silence and darkness. It is about sharing the load with the downtrodden. It is about being there for the ones who can offer nothing in return. It is about giving up your own life for the lives of others.
Read the Bible. Read the Gospels. Get to know the real Jesus. Decide for yourself what it means to be ashamed of Jesus and what it means to proclaim his love to the nations.