Jesus points out that not all persons who give to the poor, pray, and fast are not experiencing the kingdom of heaven. In fact, he makes the claim that they are hypocrites based on something that can only be seen by God - motivation.
Motivation is the underlying reason for doing something. It’s the “why” that drives a person forward to action.
Hypocrisy is using heavenly means for earthly gains.
Treasure can also be translated lock box.
Putting things in your lock box for this world vs. kingdom of heaven:
1. Ease / Convenience vs. Sacrifice
2. A God you can control vs. Submission
3. Recognition / Respect vs. Servant’s Heart
If you aim for any of these treasures you certainly will obtain them. That is the difficult thing about this kind of hypocrisy. It works! And that is why it is dangerous.
Righteousness can be harmful. Martin Luther often insisted that our righteousness is more dangerous than our sin. For “righteousness” can serve the most self-centered of all human desires: self-glorification
Frederick Dale Bruner - Matthew: A Commentary: The Christbook
The hypocrisy Jesus talks about is like a noxious gas which is unseen but nevertheless dangerous. For while only God can detect motivation in the moment, everyone will see the impacts of motivation in the end. The danger is that we may not know until it’s too late.
All motivations point toward what is important in our lives. Is faith in Christ the driving motivation? If so, you will find the kingdom of heaven is the treasure that never fades.