Jesus begins the Sermon on the Mount with "Blessed are the poor in spirit, for theirs is the kingdom of heaven.” Similarly, He begins the “Sermon on the Plain” with “"Blessed are you who are poor, for yours is the kingdom of God.” (Luke 6:20)
Does it seem strange that Jesus would begin these speeches by equating poverty with being blessed (or happy)? Later Jesus says, "Do not store up for yourselves treasures on earth, where moth and rust destroy, and where thieves break in and steal. But store up for yourselves treasures in heaven, where neither moth nor rust destroys, and where thieves do not break in or steal; for where your treasure is, there your heart will be also.” (Matthew 6:19-21)
Jesus, who was often criticized for being with sinners and who famously said to the religious leaders who did not believe Him, “the tax collectors and prostitutes will get into the kingdom of God before you.” (Matt 21:31), understood that His teachings would be most clear to those whom the world had not been kind to. Jesus’s message will be appreciated by those who know what it means to be destitute and without hope in this life, those who know from experience that you will not find enduring happiness with anything in this world and those who can clearly see their own shortcomings and comprehend their need for a Savior.
James, perhaps thinking of these words of Jesus, said (James 2:5), “did not God choose the poor of this world to be rich in faith and heirs of the kingdom which He promised to those who love Him?” Jesus said it will be difficult for the rich to enter the kingdom of heaven (Luke 18:24-27). (Difficult but not impossible for with God all things are possible.) Why? Because it is difficult for the rich to truly place their trust in the eternal Jesus ahead of temporal wealth. Jesus desires for His kingdom those who put their complete faith in Him as the author of eternal salvation (Hebrews 2:10, 12:2).
The first key to happiness: the attitude, whether poor or rich in this life, of being poor in spirit. Those who have this attitude can find happiness and eternal treasure in His kingdom, through faith in His eternal promises.