Ezekiel 18:21-28 / Matthew 5:20-26
A piggy-bank is the common name for a coin container used by children. They usually are in the design of a piglet or some other kinds of animals.
The purpose is to instill in children the habit of saving and being thrifty.
In the past, a piggy-bank is usually made of ceramic with a slot for putting in the coins. When it is full, the children would bring it to the bank and have the money deposited into their bank account and they would receive a new piggy-bank.
Because in the past, a piggy-bank has no other openings other than the coin-slot, so that the children cannot take out the money in it, other than breaking it, which is not likely what the children would do.
At times, we may think that all the good that we do is stored up in a piggy-bank somewhere in heaven, and when we go to heaven, that spiritual piggy-bank will be a testimony of how good we have been on earth.
Yet, at the same time, some may think that all the good that they have done will guarantee them the reward of heaven.
Just as pride comes before the fall, they may become complacent in their faith and slip into vice and sin.
That is what the 1st reading is pointing out if the upright man renounces his integrity, commits sin, copies the wicked man and practises every kind of filth, he will be severely punished. All the good that he has done will be forgotten, will not be counted at all.
We shouldn't be surprised at this because the good that we do flows from our faith which is a gift from God. We can't claim any credit for the good we do. In fact it is our duty to do good because our mission is to be a sign of God's goodness to others.
So if our virtue goes no deeper than just keeping the letter of the law, like not killing or murdering, and expecting to be rewarded for just that, then we will be in for a surprise.
So being upright and doing good is not for reward in heaven or saving up credit in a spiritual piggy-bank.
Being upright and virtuous is our duty to God and our obligation to our fellow human beings. In the end, we can only say we are poor and humble servants of God who did our best to fulfill our duty.