Take the risk
In order to gain confidence you must take the risk you do not want to take. Fear tells us that no risk is worth it. The feelings you experience can be extremely uncomfortable. Yet, learning to be comfortable being uncomfortable while feeling your feelings and taking risks is an important ingredient in becoming who you are meant to be in Christ. Therefore, the only way you will build confidence is to do the thing you fear. See Gideon, Esther, Moses, Simon Peter, for more details. Invite someone to take a closer look at Christ and his church.