The kingdom of God is already in this world

Luke 17:20

New American Standard Bible (NASB)

20 Now having been questioned by the Pharisees as to when the kingdom of God was coming, He answered them and said,“The kingdom of God is not coming with [a]signs to be observed;

Matthew 12:28

New American Standard Bible (NASB)

28 But if I cast out demons by the Spirit of God, then the kingdom of God has come upon you.

The kingdom of God in this world has a message to be proclaimed 

Luke 4:42-43

New American Standard Bible (NASB)

42 When day came, Jesus left and went to a secluded place; and the crowds were searching for Him, and came to Him and tried to keep Him from going away from them. 43 But He said to them, “I must preach the kingdom of God to the other cities also, for I was sent for this purpose.”

The kingdom can be seem through its supernatural component

Luke 9:27-36

New American Standard Bible (NASB)

27 But I say to you truthfully, there are some of those standing here who will not taste death until they see the kingdom of God.”

The Transfiguration

28 Some eight days after these sayings, He took along Peter and John and James, and went up on the mountain to pray.29 And while He was praying, the appearance of His face became different, and His clothing became white and[a]gleaming. 30 And behold, two men were talking with Him; and they were Moses and Elijah, 31 who, appearing in [b]glory, were speaking of His departure which He was about to accomplish at Jerusalem. 32 Now Peter and his companions had been overcome with sleep; but when they were fully awake, they saw His glory and the two men standing with Him. 33 And as [c]these were leaving Him, Peter said to Jesus, “Master, it is good for us to be here; let us make three [d]tabernacles: one for You, and one for Moses, and one for Elijah”—not realizing what he was saying. 34 While he was saying this, a cloud[e]formed and began to overshadow them; and they were afraid as they entered the cloud. 35 Then a voice came out of the cloud, saying, “This is My Son, My Chosen One; listen to Him!”36 And when the voice [f]had spoken, Jesus was found alone. And they kept silent, and reported to no one in those days any of the things which they had seen.

To enter the kingdom is the same as being saved 

Matthew 19:24-26

New American Standard Bible (NASB)

24 Again I say to you, it is easier for a camel to go through the eye of a needle, than for a rich man to enter the kingdom of God.” 25 When the disciples heard this, they were very astonished and said, “Then who can be saved?” 26 And looking at them Jesus said to them, “With people this is impossible, but with God all things are possible.”

The kingdom, although already here, is not yet complete. That is why it is said to be still in the future. They call this the "already but not yet. "

Luke 21:25-31

New American Standard Bible (NASB)

The Return of Christ

25 “There will be [a]signs in sun and moon and stars, and on the earth dismay among nations, in perplexity at the roaring of the sea and the waves, 26 men fainting from fear and the expectation of the things which are coming upon the [b]world; for the powers of [c]the heavens will be shaken. 27 Then they will see the Son of Man coming in a cloud with power and great glory. 28 But when these things begin to take place, straighten up and lift up your heads, because your redemption is drawing near.”
29 Then He told them a parable: “Behold the fig tree and all the trees; 30 as soon as they put forth leaves, you see it and know for yourselves that summer is now near. 31 So you also, when you see these things happening, [d]recognize that the kingdom of God is near.

What does it mean to be in the kingdom?

Colossians 1:9-14

New American Standard Bible (NASB)

9 For this reason also, since the day we heard of it, we have not ceased to pray for you and to ask that you may be filled with the [a]knowledge of His will in all spiritual wisdom and understanding, 10 so that you will walk in a manner worthy of the Lord, [b]to please Him in all respects, bearing fruit in every good work and [c]increasing in the [d]knowledge of God;11 strengthened with all power, according to [e]His glorious might, [f]for the attaining of all steadfastness and [g]patience;joyously 12 giving thanks to the Father, who has qualified us[h]to share in the inheritance of the [i]saints in Light.

The Incomparable Christ

13 [j]For He rescued us from the [k]domain of darkness, and transferred us to the kingdom of [l]His beloved Son, 14 in whom we have redemption, the forgiveness of sins.

1. Kingdom citizenship gives us permanent freedom from the power of Satan v13-14

2. Kingdom citizenship gives us permanent gives us permanent freedom from the penalty and power of sin.