Matthew 21:28-32, "two sons" -
Most of us are familiar with the parable (story) of the prodigal son (better titled "the forgiving father") where two sons are involved. A lesser known story is that contained here in Matthew's gospel, where again two sons are the primary characters. In this case the sons again represent the outcasts of Israel on the one hand, and the religious leaders on the other. Ironically (tragically) the modern church in the West more closely resembles the second son who says yes, but doesn't truly go!
The majority of our time and energy as apprentices (disciples) to Christ should be spent doing (abundant) life, the triangle, rather than wasting "His time" doing "church", the box. (See link below)
Dale Bruner in his commentary on this parable (his own and a collection of the best accepted others over time) clearly emphasizes the dichotomy here that Jesus pointed to often during His ministry.
The "famous", the noticeable "Christians" (churches & ministries) are quite often the second son who says yes, but doesn't go, whereas those who truly go are often the unnoticed. Big fancy buildings and programs, wealthy well-dressed peddlers of a "prosperity gospel", etc. in our time are no different than the religious leaders (e.g. Pharisees) of Jesus time on earth.
We must remember that He said "Go". Our time spent in corporate worship in our "boxes" on Sunday mornings is and should be only a very small part of following Jesus. Most of it should be a 24/7 desire and effort to reflect our Savior in our daily lives, wherever and to whomever He takes us.