Under the New Covenant, is Divination allowed?

Don't think so, no. If you use the methods of divination, whichever you may use, to get knowledge from God, then no, it's allowed. I've seen in several Renaissance works by monks and philosophers that you should entreat God and his clemency to obtain communication and knowledge from him.

The same argument against homosexuality is used here; it's in the Old Testament, so it must be valid, despite that the Old Testament isn't valid anymore.

Very nice of you to mention the latin form however, it also comes from the latin word "divinationem ' which means "the power of foreseeing, prediction. It would seem from your question and your additional details that you are trying to mislead someone or cause doubt. Divination is a sin according to scripture both in the Old and New Testament. God does not change what He says is sin under the Old Covenant and then permit sin under the New Covenant.

FYI, the Hebrew word in the Old Testament is "qesem" meaning witchcraft.

As A former Christian I can tell you the answer is yes - if it's a revelation from God. Something your definition seems open to. If it's a revelation that's not from God, the answer is no because it is assumed demonic. But I don't know that the Bible addresses the second part specifically, it may just be Christian teachings.

The apostle John was suppose to have visions from God. That's how the book of Revelations came to be.

Divination is the practice of trying to get something revealed to you WITHOUT god. When your relationship with God is such, that you no longer have communication with him, can no longer receive answers from prayers, can no longer use him to help distinguish the truth of all things... it is then that people turn to divination.

Being that as it is, you can see that divination is not of God, therefore the things you receive from it are always in question.

Christians recognize that divination is against the will of God. Most of us don't subscribe to it, give or take a horoscope here and there to pass away time on lunch breaks.

**Biblical definition of "divination" or "soothsayer" is as follows: "the practice of attempting to foretell future events or discover hidden knowledge by occult or supernatural means"

Examples forbidding divination in the Bible:

"There shall not be found among you any one that maketh his son or his daughter to pass through the fire, or that useth DIVINATION, or an observer of times, or an enchanter, or a witch." (Deuteronomy 18:10)

"For these nations, which thou shalt possess, hearkened unto observers of times, and unto DIVINERS: but as for thee, the LORD thy God hath not suffered thee so to do." (Deuteronomy 18:14)

Many people may not be familiar with the term 'divination', but such practices were well-known in Bible times and are becoming more common today. The Bible plainly condemns them.

The Jews used Divination all the time, borrowed from the even more Ancient Egyptians