My faith is a personal thing  

It's true that only you (and God!) know the state of your relationship to Him, but...

The gospel means "good news". If you don't think it's worth sharing then something is wrong somewhere isn't it? Ephesians 2:10 says that Christians are created to "do good works". It doesn't say everyone is supposed to go and preach on the street corners, but it must mean that genuine Christian faith is supposed to be visible.

If we look in the Gospels and Acts it is clear that the early church didn't hide in a corner quietly examining each other's personal faith.

Different people have been given different gifts - God doesn't make everyone (fortunately!) a street corner preacher. But God does expect us to develop and use the gifts and abilities he has given us. He's also relying on his church do show the world what he is like, and what he is offering.