Kingdom of Heaven and Kingdom of God

QUESTION: Do the expressions "kingdom of heaven" and "kingdom of God" mean one and the same thing?

ANSWER: Yes, also "the kingdom of Christ," "the kingdom of Christ and of God" (Eph. 5:5), "the kingdom of David," the ancestor and type of the Messiah (Mark 11:10), and "the kingdom" (Matt. 8:12). They are all synonymous, signifying the glorious reign of Christ in the hearts of believers. This definition the enemies of the Messiah did not like. Hence they crucified him.

— Steele's Answers, pp. 227, 228.