There is something unbalanced about laws. If you break a law, you can get punished. But if you keep all the laws, no matter how carefully – if you never speed, and you never jaywalk and you always return your library books by the due date – there is no reward. The laws simply define how any respectable member of society is supposed to behave. Any failure to follow the least letter of the law makes you a deviant liable to be punished, but you do not deserve any reward for obeying the laws because all you have done is what you were supposed to do in the first place.
In chapter 3 of Paul’s letter to the Romans, Paul says that “all people have sinned and fall short of the glory of God”. It is a bit remarkable that most people seem to think that they can earn a place in heaven by obeying God’s laws, when Paul made it abundantly clear that if you fail to keep all of God’s laws then you no longer deserve a place in heaven. And the problem is that no-one except Jesus has ever managed to live life without breaking any of God’s laws.
Fortunately the story does not end there. We can be freely justified by God’s grace through the redemption provided by Christ Jesus. That is why we cannot boast about anything, because we have not done anything to boast about. We do not deserve to get to heaven. We have not made the grade. But Jesus has died to cancel out our sins, and so God lets us in if we have faith in Jesus.