>>>>>>>>>> Does this phenomenon happen today?
Some believe this scripture implies that it will happen again.
"But as the days of Noah were, so also will the coming of the Son of Man be." Matt24:37
(The days of Noah included the Sons of God taking to wife the daughters of men)
Jesus did not say that anything abnormal in the state of society in Noah's day would resemble human society in the last days. Taking the passages in Matthew 24 and Luke 17, we can make a complete list of the features in which the two ages would resemble each other, namely, people would be 1) getting married, 2) Eating and drinking 3) buying and selling. As anyone can see, there is nothing particularly sinister about any of these activities, and they are, in fact, activities common to all people of every age (even good people).
If Jesus wished to suggest that there would be special, evil things going on in the end of time, He did not pick a very good list of activities to indicate this thought. Why did He not say, "They will be raping, and pillaging, and murdering, and worshipping demons"? These things were, no doubt, happening in the days of Noah (as well as at almost every era in human history, including our own). However, these were not the kind of activities that Jesus wished to underscore. His point was that, in the days of Noah, even though the devastating judgment of God was impending, the people thoughtlessly went about their everyday, normal, legitimate activities—totally oblivious to the danger they were in. It is in only this respect that Jesus drew a parallel to these people and those who will be living just prior to the final judgment.
>>>>>>>>>>> How would you recognize them?
"...to another discerning of spirits." 1 Cor 12:10
Is it your opinion that the gift of discerning of spirits, to which Paul refers, was a gift intended to discern the species of another person's parents? In the context, I would understand it considerably differently.
>>>>>>>>>> What would happen to a Christian if she accidentally married one?
I'm not sure that the words "Christian" and "accidentally" fit well together.
They don't. Accidentally marrying a bad person does not fit well with anyone. Unfortunately, though, it happens far too frequently. I was a Christian when I made a mistake in marriage, believing my wife to be a true convert. It does not take much experience in the presence of Christian couples to come to the conclusion that Christians often make poor and misinformed marriage choices. So Brody's question would still invite an answer.
>>>>>>>>>> Should we preach the gospel to those whom we have identified as such?
It would seem so. "And He said to them, "Go into all the world and preach the gospel to every creature." Mark 16:15
Should we expect a different kind of reaction to the Gospel from these half-humans than we might expect from humans? For example, can these "creatures" repent? If so, will they be cured of their half-human condition and made into whole men?
>>>>>>>>>> What is the criteria for figuring out that one is the offspring of a fallen angel?
How about this?
"and every spirit that does not confess that Jesus Christ has come in the flesh is not of God...." 1John 4:1-3
John certainly has given us a way to recognize a wrong spirit in the false prophets, which is what John is referring to (v.1). However, this test would not be of much use in distinguishing between a mere heretical false prophet, on the one hand, and demon-engendered half-man, on the other. I would hope to have something more specific as a test that would identify such a specific type of mutant being—at least, if it was important for us to know about them! Of course, if there is no need for us to know about them, then there is, arguably, no need for this thread.
