The devil will harm you even if you know him and the angel will do good even if you don't know him.
But it depends on what you want. 😂

As a human, who's terrified of the unknown I would rather let the angel prove they're an angel rather than blindly accepting it at face value.....
(And I'm not bringing up Lucifer's case here!)
Yes! Lucifer is the anomaly but still a yardstick that not all angels are angelic!