2 Timothy 1:7 - ""For God did not give us a spirit of timidity, but a spirit of power, of love and of self-discipline."" (NIV)
It's okay to be afraid. Even when you put up a strong face, the bravest of us are often nervous inside. Yet God is there with us to provide strength in the face of the things we fear most. For a lot of us, we often water down or hide our faith, because we fear a lack of acceptance by others. It's a normal feeling. We want to be liked and loved. We want to have friends. However, watering things down to where we lose our faith means giving into those fears rather than using God's spiritual gifts.
It is not easy to stand up and say, "I believe," but you will feel better in the long run for it. True friends will accept your faith as part of who you are and love you for it. Your courage to express your faith may inspire others to come to Christ or give them the courage to stand beside you and tell others that they, too, believe. Sometimes that stand may bring about some teasing, and in some cases it may bring about a loss of friends, but if those friends cannot accept our faith, what good are they anyhow? God promises a gift of strength is we seek it. He put it in our inner nature, and we just need to look for it.