We begin with the prophecy for day/age 1 from Genesis 1.

Then God said, “Let there be light”; and there was light.  And God saw that the light was good; and God separated the light from the darkness.  And God called the light day, and the darkness He called night.  And there was evening and there was morning, one day.  Genesis 1:3-5   NASB

God Almighty’s nature is described as light.

And this is the message we have heard from Him and announce to you, that God is light, and in Him there is no darkness at all.  1John 1:5  NASB

So, if God Almighty already existed as light, why would He need to speak light into existence?  Well, the light that God Almighty brings forth in this first day/age is not His light or nature, but a realm of light for humanity–the kingdom of God/light–that has been manifested, as we will see, in both the physical and the spiritual realms.

In addition, God Almighty created the spiritual realm of darkness.

The One forming light and creating darkness, Causing well-being and creating calamity; I am the LORD who does all these.  Isaiah 45:7  NASB

“to open their eyes so that they may turn from darkness to light and from the dominion of Satan to God, in order that they may receive forgiveness of sins and an inheritance among those who have been sanctified by faith in Me.”  Acts 26:18  NASB

For He delivered us from the domain of darkness, and transferred us to the kingdom of His beloved Son,  Colossians 1:13  NASB

These scriptures identify light and well-being with the kingdom of God Almighty and darkness and calamity with the kingdom/domain of Satan.  In the natural, the light is day and the darkness is night (Gen 1:5), and the same association is true in the spiritual.

for you are all sons of light and sons of day.  We are not of night nor of darkness;  1Thessalonians 5:5  NASB

Putting this together, we have the light manifested in the first day/age is a spiritual realm known as the kingdom of light or the kingdom of God Almighty or the kingdom of heaven.  The darkness spoken of is a spiritual realm known as the kingdom of darkness or the kingdom of Satan or domain of Satan.  These two kingdoms are not physical places; they are spiritual realms which include spiritual entities as well as humans.  God Almighty separated these two realms (Gen 1:4), which means that one cannot be simultaneously a member in both of these kingdoms.

“No one can serve two masters; for either he will hate the one and love the other, or he will be devoted to the one and despise the other.  You cannot serve God and mammon [money, possessions, fame, statue, or whatever is valued more than the Lord].”  Matthew 6:24  AMP (Amplified Bible)

“He who is not with Me is against Me; and he who does not gather with Me, scatters.”  Luke 11:23  NASB

One can be in the kingdom of light in this life as well as in the afterlife.  Similarly, one can be in the kingdom of darkness in this life as well as in the afterlife.

The spiritual realm of light, called the kingdom of God, includes God Almighty, Jesus Christ, and the Holy Spirit.

That men may know from the rising to the setting of the sun that there is no one besides Me.  I am the LORD, and there is no other.  Isaiah 45:6  NASB

God Almighty created and structured the world we live in.

For in Him all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities – all things have been created through Him and for Him.  And He is before all things, and in Him all things hold together.  Colossians 1:16-17  NASB

In addition to the Trinity, there are angels and the “heavenly host.”

And suddenly there appeared with the angel a multitude of the heavenly host praising God, and saying,  Luke 2:13  NASB

The heavenly host singing at Jesus’ birth might have included some of those who, after their death, joined the kingdom of God in the afterlife.

“And I say to you, that many shall come from the east and west, and recline at table with Abraham, and Isaac, and Jacob, in the kingdom of heaven;”  Matthew 8:11  NASB

And He was saying to them, “Truly I say to you, there are some of those who are standing here who shall not taste of death until they see the kingdom of God after it has come with power.”  And six days later, Jesus took with Him Peter and James and John, and brought them up to a high mountain by themselves.  And He was transfigured before them; and His garments became radiant and exceedingly white, as no launderer on earth can whiten them.  And Elijah appeared to them along with Moses; and they were conversing with Jesus.  Mark 9:1-4  NASB

Peter, James, and John were those whom Jesus said would see the kingdom of God before death, and these apostles saw evidence of the kingdom of God in a transfigured Jesus and a resurrected Elijah and Moses.

We find that Abraham, Isaac, Jacob, Elijah, and Moses after their deaths are specifically named as members of the kingdom of God.  Still others are added.  Here is a request from one of the criminals who was crucified with Jesus.

And he was saying, “Jesus, remember me when You come in Your kingdom!”  And He said to him, “Truly I say to you, today you shall be with Me in Paradise.”   Luke 23:42-43  NASB

It is the belief of faithful Christians, and is offered as hope to lost souls, that they will join the heavenly host.

There is another characterization of the kingdom of God/light.

Again therefore Jesus spoke to them, saying, “I am the light of the world; he who follows Me shall not walk in the darkness, but shall have the light of life.”  John 8:12  NASB

Jesus said to him, “I am the way, and the truth, and the life; no one comes to the Father but through Me.”  John 14:6  NASB

Thus, life is associated with Jesus and the kingdom of light.

Now, let’s look at spiritual darkness.

For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness; against the spiritual forces of wickedness in the heavenly places.  Ephesians 6:12  NASB

Chief among the spiritual forces of wickedness in the spiritual darkness is Satan.

And he laid hold of the dragon, the serpent of old, who is the devil and Satan, …  Revelation 20:2  NASB

First, notice that Satan and the devil are two names for the same thing.  We will consistently refer to this entity as Satan.  In Genesis 3, Satan is represented symbolically as a serpent (the serpent of old) and then in Revelations he is represented as a dragon.  In other places in the Bible, Satan is identified by name without any symbolism.

Satan is joined in the kingdom of darkness by angels, evil spirits and demons.

And the great dragon was thrown down, the serpent of old who is called the devil and Satan, who deceives the whole world; he was thrown down to the earth, and his angels were thrown down with him.  Revelation 12:9  NASB

Just as God Almighty sends His angels to minister to His saints, Satan sends his evil spirits and demons to afflict humanity.

And He healed many who were ill with various diseases, and cast out many demons; and He was not permitting the demons to speak, because they knew who He was.  Mark 1:34  NASB

At that very time He cured many people of diseases and afflictions and evil spirits; and he granted sight to many who were blind.  Luke 7:21  NASB

and also some women who had been healed of evil spirits and sickness: Mary who was called Magdalene, from whom seven demons had gone out,  Luke 8:2  NASB

so that handkerchiefs or aprons were even carried from his body to the sick, and the diseases left them and the evil spirits went out.  Acts 19:12  NASB

The antithesis of light and life is darkness and death.  /  “Have the gates of death been revealed to you?  /  Or have you seen the gates of deep darkness?”  Job38:17 NASB

Since then the children share in flesh and blood, He Himself [Jesus] likewise also partook of the same, that through death He might render powerless him who had the power of death, that is, the devil;  Hebrews 2:14  NASB

Whereas God Almighty and Jesus bring light and life to humanity, Satan and his assistants bring darkness and death.

Though the kingdoms of light and darkness are mutually exclusive, it is possible to move between them.  The redemptive work of Jesus is the means by which one can transfer from the kingdom of darkness into the kingdom of light.

For He delivered us from the domain of darkness, and transferred us to the kingdom of His beloved Son,  Colossians 1:13  NASB

Likewise, it is possible to move from the kingdom of light to the kingdom of darkness.

For if God did not spare angels when they sinned, but cast them into hell and committed them to pits of darkness, reserved for judgment;  2Peter 2:4  NASB

And angels who did not keep their own domain, but abandoned their proper abode, He has kept in eternal bonds under darkness for the judgment of the great day.  Jude 6  NASB

The strong similarity in these two verses suggests that they speak of the same, angelic event.  First, notice that we are not told when the angels sinned in relation to other events in the Bible.  Second, notice that these angels, for an unspecified period of time, kept their proper abode, which implies that they were obedient before they sinned.  Third, the consequence of sinning for these angels is that they were placed in eternal bonds under darkness and reserved for judgment by redeemed humanity.

Do you not know that we shall judge angels? How much more, matters of this life?  1Corinthians 6:3  NASB

But unlike humanity, these fallen angels have not and will not receive the benefit of Jesus’ work of redemption.

For assuredly He does not give help to angels, but He gives help to the seed of Abraham.  Hebrews 2:16  NASB

Here are other translations of this scripture.

Jesus helps Abraham’s descendants rather than helping angels.  Hebrews 2:16  GW (GOD’S WORD)

For, as we all know, He [Christ] did not take hold of angels [the fallen angels, to give them a helping and delivering hand], but He did take hold of [the fallen] descendants of Abraham [to reach out to them a helping and delivering hand].  Hebrews 2:16  AMP

For surely it is not angels he helps, but Abraham’s descendants.  Hebrews 2:16  NIV (New International Version)

Sinful angels do not have a means of restoration as do Abraham’s seed/descendants.

Regardless which kingdom one is in, s/he can have interactions with either kingdom.

Then Jesus was led up by the Spirit into the wilderness to be tempted by the devil.  Matthew 4:1  NASB

Here we are told that a human, Jesus, has interactions with the Spirit from the kingdom of light and with the devil from the kingdom of darkness.

The kingdom of darkness is a counterfeit of the kingdom of Light, for that which Satan produces is generally a counterfeit of what God Almighty does.  Consequently, the manifestation of these two spiritual kingdoms in humanity will have a similar structure.  The following table, derived from the booklet The Two Kingdoms by Bill Britton, displays the two kingdoms in greater detail than is necessary for our study.

The structure of these kingdoms offers insight into the array of spiritual forces that humanity encounters while on earth.  For emphasis, we repeat a previous verse.

For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places.  Ephesians 6:12  NASB