It seems as if we have more grace today because we can sin over and over and over again, without necessarily being punished my God, but one offense to God in the Old Testament brought about immediate punishment.
Good question, @Pastor.Trav.
And in one way I can see what you’re saying - but in another, I’m not sure your simplification of things is entirely accurate.
The only people I can think of in either Testament who were immediately punished by God for committing only one offense were Adam and Eve. But then, their one offense catastrophically corrupted the “spiritual DNA” of the entire human race - which was a pretty unique event.
Now, there are other occasions where it may look like people were being punished for one event. When the Israelites worshipped the golden calf, for instance, in Exodus 32 - or when they refused to cross the Jordan for fear of the giants in the land in Numbers 14.
But if you zoom out and consider the fuller story, you see that these weren’t so much one-time offenses as they were the “straw that broke the camel’s back” - the culmination of a series of offenses that God finally dealt with when their pattern of stubborn rebellion demanded stronger measures (Hebrews 3:7-11).
But throughout the Old Testament, God consistently shows Himself to be a gracious and merciful God (Exodus 34:6-7).
And in the New Testament, there are occasions when His judgment appears to come down severely on people for what may, at first glance, appear to be isolated sins - Ananias and Sapphira in Acts 5, for example. Or Simon the magician in Acts 8.
I also think there’s another thing to consider in such stories. In either Testament, we see the principle that to whom more light is given, more is expected. People who had less revelation from God were given more rope than those who received greater light.
So a man collecting sticks to start a fire on the Sabbath when God was so miraculously evident among the people in the days of Moses might not have been tolerated so easily as a man in another generation when God seemed so silent and distant.
When Ananias and Sapphira saw God’s miracles daily at the hands of the apostles, what on earth made them imagine that they could get away with lying to the Holy Ghost?
I would say that anyone who has the attitude that they “can sin over and over and over again, without necessarily being punished by God” is drifting on a current that is headed for a waterfall!
But I do get the point that God does seem to deal overall more graciously and less harshly with His people in the New Testament than in the Old. I think Galatians 3:24-25 and Galatians 4:1-7 give us some insight on this.
Anyone who has raised children to adulthood recognizes that your relationship with your children when they were minors living under your roof, beholden to your rules, whom you were responsible to provide for and to train up - your relationship with them then was very different from what it became after they left home, became established on their own, became responsible adults.
In many ways, God treated Old Testament believers like minor children still needing the guidance of a disciplinarian, a schoolmaster (Galatians 3:24-25) - they were treated very much like servants learning to become responsible for their chores (Galatians 4:1-3).
But in the New Testament, God treats us more like adult sons who have come of age, who are responsible enough to inherit and manage the gifts of the Spirit with a maturity that was uncommon in the Old (Galatians 4:4-7).
And the reason is because the Spirit of His Son now permanently indwells our hearts (Galatians 4:6-7). That puts the lowliest New Testament saint on a completely different level from the greatest Old Testament prophet (Matthew 11:11). While all of those ancient saints were saved by the same faith we are, they did not all have the same privileges we do today (Hebrews 11:39-40).
We can see Jesus, on the night of His betrayal, revealing this change in the relationship to His disciples in John 15:15.
And, of course, people who have been transformed by the indwelling Spirit will not have a childish attitude that wants to sin all it can without being punished.
I do not mean the flesh on the outside, of course. The fallen flesh will crave sin until the day it dies. But the Spirit on the inside will cringe from sin, because it is grieved and vexed by it.
I hope this will help you with this question.