They took the very same oaths that they took when they betrayed God. It's the same oath now as then.

For those of you that don't believe we are fighting evil, spiritual evil, think very hard again about that.

Book of Enoch

Chapter 7 [SECT. II.]

1. It happened after the sons of men had multiplied in those days, that daughters were born to them, elegant and beautiful.

2. And when the angels, the sons of heaven, beheld them, they became enamoured of them, saying to each other, Come, let us select for ourselves wives from the progeny of men, and let us beget children.

3. Then their leader Samyaza said to them; I fear that you may perhaps be indisposed to the performance of this enterprise;

4. And that I alone shall suffer for so grievous a crime.

5. But they answered him and said; We all swear;

6. And bind ourselves by mutual execrations, that we will not change our intention, but execute our projected undertaking.

7. Then they swore all together, and all bound themselves by mutual execrations. Their whole number was two hundred, who descended upon Ardis, which is the top of mount Armon.

8. That mountain therefore was called Armon, because they had sworn upon it, and bound themselves by mutual execrations.

9. These are the names of their chiefs: Samyaza, who was their leader, Urakabarameel, Akibeel, Tamiel, Ramuel, Danel, Azkeel, Saraknyal, Asael,

   Armers, Batraal, Anane, Zavebe, Samsaveel, Ertael, Turel, Yomyael, Arazyal. These were the prefects of the two hundred angels, and the remainder were all with them.

10. Then they took wives, each choosing for himself; whom they began to approach, and with whom they cohabited; teaching them sorcery, incantations, and the dividing of roots and trees.

11. And the women conceiving brought forth giants,

12. Whose stature was each three hundred cubits. These devoured all which the labour of men produced; until it became impossible to feed them;

13. When they turned themselves against men, in order to devour them;

14. And began to injure birds, beasts, reptiles, and fishes, to eat their flesh one after another, and to drink their blood.

15. Then the earth reproved the unrighteous.