Any woodcroft book in particular you like?

"Angelic Protection Magick" is a good one.

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Are these books good for getting closer to God and developing the self?

I think that is on you and how you use them. Be thankful not only to the angel(s), but to God who created them. Invoke in Jesus' name, etc.

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Do you trust the beings in these books?

Yes, that book in particular; he selects angels that are safe.