I can't help but to put myself in the shoes of the women at the tomb that first Easter morning.  Here you have a non-human entity (an angel) telling the women that it can read their minds (it knows why they are there and who they seek) and that Jesus, whom they saw die, is no longer dead!  Then it tells them not to be afraid!  How could you help but be afraid!

Maybe one couldn't help but be terrified at that scene, but there is something to be said about the admonition to not be afraid.  Because of what has happened, as unusual and frightening as it might have been, we really don't have to be afraid anymore; we need not fear death because we know that eternal life follows it for those of us who have faith in Jesus as our Lord and Savior.  We need not fear all of the bad things that happen to us, because Jesus said that He will never leave us or forsake us.  We never need to fear loneliness again, because the Spirit is with us always. We need not fear judgement, because our sins have been forgiven!