John 5:43
I have come in my Father’s name, and you do not accept me; if another comes in his own name, you will accept him.

Revelation 17:13
These are united in yielding their power and authority to the beast

Satan, according to those who've seen him - is covered in blisters, burns and sores...
Yes, he can disguise himself as an Angel of Light.
But when he's "himself" he is "a burnt looking wretch"

According to St Catherine of Siena, although Satan incites people to sin, he is loathe to hang around to see the sin carried out.
Christ said to St Catherine that it is due to Satan's (and the other fallen host) angelic nature, that he can not stand to witness acts of impurity.
He tempts us to sin merely to ensure we are damned. If we seem to repent, he sees to it that we are tempted again.
He can not abide, immorality himself, it is merely due to his wickedness that he uses the black arts/Sorcery to inspire us to sin, since his strength is far greater than ours because he is an Angel.
He inspires us to sin FIRST, and then loathe to witness that act, he flees from us.
Pity those he inspires to concupiscence did not understand it. It is only CHRIST, St Michael or Our Lady who are able to defeat him.

In this text, Our Lord is discussing with St Catherine the issue of Homosexuality in His Priesthood
books.google.co.uk/books/about/The_Dialogue.html=onepage&q&f=false