"Matthew is the only one of the four Gospel narrators who uses 'kingdom of heaven', there are five places where he switches to 'kingdom of God'; and all five show that he uses the two terms convertibly, as practical equivalents." J. Sidlow Baxter
1. Requirement for Entrance
'Then said Jesus unto his disciples, Verily I say unto you, That a rich man shall hardly enter into the kingdom of heaven. And again I say unto you, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God." Matthew 19:23-24
2. Righteousness of its Subjects
"But seek ye first the kingdom of God, and His righteousness; and all these things shall be added unto you." Matthew 6:33
"Blessed are they which are persecuted for righteousness' sake: for theirs is the kingdom of heaven." Matthew 5:10
"For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven." Matthew 5:20
3. Resistance by its Foes
"But when the Pharisees heard it, they said, This fellow doth not cast out devils, but by Beelzebub the prince of the devils. But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you." Matthew 12:24,28
"And from the days of John the Baptist until now the kingdom of heaven suffereth violence. For John came neither eating nor drinking, and they say, He hath a devil." Matthew 11:12,18
4. Responses to its Invitations
"Verily I say unto you, That the publicans and the harlots go into the kingdom of God before you. For John came unto you in the way of righteousness, and ye believed him not: but the publicans and the harlots believed him" Matthew 21:31,32
"John the Baptist, preaching in the wilderness of Judaea, and saying, Repent ye: for the kingdom of heaven is at hand" Matthew 3:1,2
5. Rejection to its Offer
"Therefore say I unto you, The kingdom of God shall be taken from you, and given to a nation bringing forth the fruits thereof" Matthew 21:43
"The kingdom of heaven is like unto a certain king, which made a marriage for his son, and sent forth his servants to call them that were bidden to the wedding: and they would not come" Matthew 22:1,2