We must go on to show that man can reach that kingdom. Otherwise it would be hoped for and prayed for in vain. In the first place, the divine promise makes this possibility clear. Our Lord says, in Luke 12:32: “Fear not, little flock, for it hath pleased your Father to give you a kingdom.” God’s good pleasure is efficacious in carrying out all that He plans, according to Isaiah 46: 10: “My counsel shall stand, and all My will shall be done.” For, as we read in Romans 9: 19: “Who can resist His will?” Secondly, an evident example shows that attainment of the kingdom is possible.
St. Thomas Aquinas. (1265-1274). Compendium Theologiae: Possibility of Reaching the Kingdom, trans. by Cyril Vollert. St. Louis & London: B. Herder Book Co., 1947
All scripture is given by inspiration of God and is profitable for doctrine, reproof, correction, and instruction in righteousness (2 Timothy 3:16).