If you don't know God, experiencing fear is common. This is generated by not knowing what is happening or might happen. For example, people fear abandoning themselves to God. In the Gospels, we read that people saw Jesus perform some mighty, wondrous deed, were amazed, and started to fear. Now, if you know Jesus well, you have a different story. Know that God loves you dearly, you are at ease with him. And you are no longer concerned about Satan, since God now protects you. In conclusion, knowing God removes all fears.