Fallen angels
Intro
The sons of God mentioned in Genesis 6:4 are the fallen angels.
(Genesis 6:4 [KJV]) There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
Just like there exists giants on earth today I believe also that there exists unclean spirits that don't have a body that can possess people on earth today, just like in the 4 gospels.
I believe Satan is a living being, with a physical body, not just a spiritual entity and is here on earth today. He can shape shift into an angel of light and probably into many other forms as well.
I believe also that, especially during the end times, there will exist fallen angels on the earth. These fallen angels can take the form of a person, but they are not human. They cannot get saved and their purpose here on earth is to kill the believers in the Lord Jesus Christ and also to deceive the whole earth in the end times. Judas was probably a fallen angel.
They are described I believe by Jesus in the parable with the tares.
(Matthew 13:24-30 [KJV])
[24] Another parable put he forth unto them, saying, The kingdom of heaven is likened unto a man which sowed good seed in his field:
[25] But while men slept, his enemy came and sowed tares among the wheat, and went his way.
[26] But when the blade was sprung up, and brought forth fruit, then appeared the tares also.
[27] So the servants of the householder came and said unto him, Sir, didst not thou sow good seed in thy field? from whence then hath it tares?
[28] He said unto them, An enemy hath done this. The servants said unto him, Wilt thou then that we go and gather them up?
[29] But he said, Nay; lest while ye gather up the tares, ye root up also the wheat with them.
[30] Let both grow together until the harvest: and in the time of harvest I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them: but gather the wheat into my barn.
If they come and bother you then ask them to leave you alone in the name of the Lord Jesus Christ.