Why does the Bible regularly tell us not to be afraid?
Several reasons, I think...
For one, God knows our default emotion to the unknown is fear -- even though He's got it all under control.
Also, fear can keep us from faithfully following Him where He calls us. (This is why it's so important to deal with our fears.)
And finally... many times the greatest blessings are on the other side of what we fear, so there's no need to be afraid.
Don't let fear block your view of the good God is doing in your midst.
The Lord is my light and my salvation; whom shall I fear? The Lord is the stronghold of my life; of whom shall I be afraid? (Ps.27:1).