When you have taken a step of faith to base your life on something you can't see, it can be very scary to admit it to others who haven't taken that step of faith. Their reactions can be hard, their questions can be scary, their rejection can be painful. We end up thinking that we will just avoid sharing our faith with others until we are ready for all of those things. We think we just need a bit more preparation. That isn't what Jesus thought though!
Matthew 9-10
It's more important that you start than be fully prepared.