The interchangeable use of the Kingdom of God and the Kingdom of Heaven reveals how the people of the Lord Jesus’ generation understood them. A difference is apparent, but the differentiation was defined through the context of the statements.
Both the Kingdom of God and the Kingdom of Heaven include the nation of Israel, but the Kingdom of Heaven has a unique relationship to Israel.
Take notice of the following Scriptures:
Matthew 10:5-7 These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: But go rather to the lost sheep of the house of Israel. And as ye go, preach, saying, The kingdom of heaven is at hand.
Matthew 28:17-20 And when they saw him, they worshipped him: but some doubted. And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.
Compare also –
Luke 19:11 And as they heard these things, he added and spake a parable, because he was nigh to Jerusalem, and because they thought that the kingdom of God should immediately appear.
Acts 1:6 When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?
Note that the Kingdom that the disciples expected and desired to be set up was no longer preached following this time –
Acts 2:37-42 Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do? Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call. And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation. Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls. And they continued stedfastly in the apostles’ doctrine and fellowship, and in breaking of bread, and in prayers.
Nothing is said of the Kingdom of Heaven while the Kingdom of God is often preached –
Acts 8:12; 14:22; 19:8; 20:25; 28:23, 31
The Kingdom of Heaven includes both believers and unbelievers. They will be separated by God upon His return. Refer to Matthew 13:24-43; Romans 9:28,29
The ekklesia of Jesus Christ is neither Kingdom of God, Heaven, nor family of God.