In the parable of the two sons, we see something that is played out every day in our homes, our work places and in the public arena. The first son is quick to promise to do something for his father, but doesn't follow through, but the second son has a change of heart after refusing his father's request and does the will of his father.
On the theological side, we understand that Jesus is speaking to a crowd who believe that, as the Chosen People of God, they are guaranteed a place in the kingdom, but that sinners and Gentiles will not be allowed in.
But if we only reflect on this interpretation, we may miss the point for ourselves. We too may have minds that are closed to the reality that Jesus came to save everyone.
There is a joke that ends with the name of each denomination in heaven believing that they are the only ones there, so St. Peter requests that the newly admitted to the kingdom tiptoe past their closed doors so as not to spoil their day.
No one of us is guaranteed eternal life with God in heaven even though each one of us is promised eternal life. We are called to respond to God's promise by the way in which we live β with love, justice, forgiveness, compassion, in other words, doing the will of the Father.
Now some of us will have periods of rebellion β just like teenagers in a family β but the important thing is to have a change of heart, a conversion, and bring our lives back on track.
It's not enough to SAY we believe, we need to DO the will of our Father.

