We know about missions in Africa, but Why there are no missions for Christians?

missions are spread in many countries like in Africa, Asia to convert the non-Christians but why there are no missions for Who are already born Christians but far away from the Church and Christian life so whenever they seek God, they look for another religions and leave their real faith for the favor of some pagan religion like islam and do not even look in the Bible but look for strange books. Why there is nothing to let people to start reading their Bibles ?