The spiritual promise: "Lord, are you at this time going to restore the kingdom of Israel?" Acts 1:6
Israel in the old covenant is God's promise made to Abraham: "Not one of all the LORD'S good promises to Israel failed; every one was fulfilled" Joshua 21:45.
But in the new alliance, the promises are the holy spirit and eternal life: "On one occasion, while he was eating with them, he gave them this command: ´Do not leave Jerusalem, but wait for the gift my Father promised, which you have heard me speak about. For John baptized with water, but in a few days you will be baptized with the Holy Spirit´" Acts 1:4-5.
But the disciples, after Jesus was resurrected, and not having received the gifts of the Holy Spirit, still did not fully understand the new promises, that is why when Jesus introduces himself to the disciples before saying goodbye to them, he receives a question: "Lord, are you at this time going to restore the kingdom of Israel?" Acts 1:6.
Jesus is not a liberating messiah like David, Jesus did not come to establish a Kingdom or a temporary dynasty, but to give a message and to institute the Church, the continuation of his task on earth.
That's why Jesus answers them: "But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth" Acts 1:8.
The Kingdom of Heaven is a message of spiritual transformation for man, like the seed that becomes a tree or the worm that becomes a butterfly; it is not a message for natural men who follow the dictates of the body and passions, but a message for spiritual men who follow God and true life, the eternal life or contemplative activity, the kingdom of God is beyond the law of Moses or the human virtues, is the action of God among men: "Be perfect, therefore, as your heavenly Father is perfect" Matthew 5:48, "Be merciful, as your heavenly Father is merciful" Luke 6:36, "Be holy because I am holy" 1 Peter 1:16.