Having said the foregoing, we should note that capital punishment in the theocractic governance of O.T. Israel was determined solely, if it was to be done right, by the revealed will or Law of God. Israel as a community or society under God's law (as revealed thru Moses or the Mosaic Law) was to execute a criminal who was guilty of capital crimes only in a legally authorized manner after a legally conducted 'trial' under the Mosaic / Jewish law of the O.T. The first stipulation of the Law in this regard was that the guilt was to be determined at the mouth of ' two or three witnesses'. Imagine the case of: a), no witness, or b), only one witness, or c) there is no one willing to speak to witnessing the crime. Under such circumstances the law of Moses had no provision for the execution of such a person - even though they might in fact be 'most guilty' of the crime.
One could ponder this for a while and imagine a society that permitted people to be put to death based on just the 'suspicion' of someone or just the word of one 'witness' who was false(say an enemy who just wanted to get rid of someone!). Two witnesses greatly improved the odds of truth in the matter of an accusation. God's wisdom is manifest in his requirement for two or more witnesses and this was a vast improvement over the general worldly society of ancient times in dealing with such crimes. Note as well that the Mosaic law also perhaps severely limited the crimes truly worthy of death over what the surrounding worldly societies of the time would have deemed worthy of death. But here, we unnecessarily digress.
In David's case of adultery, I believe there were No civil witnesses to this great wrong done in secret (except the very two who were guilty of adultery, and they were saying nothing!). Thus, in keeping with the Mosaic law, David could not have been stoned. David's 'murder' of Uriah was contrived with no witnesses unlesss it was Joab, who was complicit and saying nothing!
However, God was a witness to all of this!. But, God as giver of that law, honored it! I don't believe anyone familiar with the 'rest of the story' would contend David's great crimes (which became in time worse and more complex, before it was fully exposed) was ignored by God. God punished David severely for his wrong and though David repented , he paid for his wrong for the rest of his life by loss of his family, reputation, and many friends turning against him. The story of it was left for all to hear and know of! The remainder of his life stands as a proverb and an quintessential illustration of the consequences of secret sins.
Now as to the case of Paul, under the Jewish civil law of his time one should recall that he was civily authorized (he 'carried letters') by the Jewish Sanhedrin and High Priests to cause Jewish converts to Christianity to be apprehended and put in prison and some put to death. This was because the non-believing Jews of Paul's locale/era in Jerusalem considered those Jews (under the law of Moses), who had become Christians, to be heretics and blasphemers.
Recall that under Jewish/Mosaic law these (heretics and blasphemers) were crimes worthy of death (again at the mouth of two or three witnesses). Finding two or three witnesses to declare that certain Jews were now indeed Christians was both easily, truthfully done. Hence, the Sanhedrin 'had a case' to cause Christians to be put to death.
Further, the Romans apparently were not involved as a civil government at this point in what the unbelieving Jews were doing to the Jewish converts to Christianity! They were not going to invoke any kind of court / verdict in these matters. I must say, too, I find no record where Paul personally caused the death directly of anyone. So, as we consider the case of Saul, we find that there were not the required two witnesses under the Jewish law to bear witness that Saul had committed a capital crime worthy of death. Saul (later Paul) was not guilty of violating Jewish civil law in any way worthy of capital punishment. In fact he was an upholder of it and in the eyes of the Jewish priests and Sanhedrin, I'm sure, deemed worthy of their utmost approval.
Now , however, consider this - Jesus still held Paul accountable (even as God in the O.T. held David accountable in the absence of the required two or more witnesses) for what he had done to the Christians of his time. Why? I think the reason is that Saul had, though acting in good conscience (Acts 23:1), succeeded in ignoring vital evidence that the Christians were not heretics and blasphemers but were in fact the true believers and obedient children of God. What evidence had Saul overlooked that he should not have overlooked? Recall, Saul was at the stoning (Acts 7:) of Stephen (though he didn't cast a stone!) and also that Jesus asked Saul on the road to Damascus (Acts 9) why he 'kicked against the pricks' and Saul knowing the O.T prophecies as he did of the Messiah had to pass by a lot.
For the rest of his life Paul dearly served Christ penitently and faithfully. Jsus said he, Paul, .."must suffer great things for His namesake."
Yes, capital punishment under certain circumstances in the O.T. and Jewish civil society was aproved, commanded, authorized, but only under those circumstances!
Hope this discussion was helpful to the querist.
After hearing his fate and the foretelling of all the awful, awaiting consequences to his sin - on top of his death - David repented:The Holy Spirit by way of the prophets wrote:So David's anger was greatly aroused against the man, and he said to Nathan, "As the Lord lives, the man who has done this shall surely die!. And he shall restore fourfold for the lamb, because he did this thing and because he had no pity."
Then Nathan said to David, "You are the man! Thus says the Lord God of Israel ..."
As was said in the previous post, outside of God, there were not enough witnesses to justify David's execution according to Jewish Law. This is why the Jews could not have executed him, permorming "capital punishment". However, God saw the crime and had senteneced David to death, using David's own judgment. Yet, when David repented, God granted some clemency in sparing David's life, even though death may have been preferred, had David been allowed it as an alternative to the devestation his family suffered as a consequence of his sins.So David said to Nathan, "I have sinned against the Lord." And Nathan said to David "The Lord also has put away your sin; you shall not die." (II Samuel 12:1-15)
Back to point, the lack of witnesses and God's clemency and mercy are the reasons why David did not suffer execution by the hand of the civil authorities or God's direct judgment.
As you mentioned in the beginning, God has clearly authorized captial punishment in both the Old and New Covenants. Now, as ultimate Lawgiver and Judge, who bestows authority to the civil governments, He has the right grant clemency and mercy as He sees fit. That is His right.
I think the important lesson, whether one is pondering capital punishment or eternal judgment, we must realize that God has demonstrated the ability and possability of granting clemency beyond what He has promised. However, we have no promise, revelation, or basis for acting upon such. In other words, whether I am looking at the thief on the cross, or David's sin with Baathsheba, I cannot presume that God will spare me in a similar way - above and beyond what He has promised.
The sin of presumption, when discussed in the Bible, is almost always connected with an immediate, capital punishment. Such people typically forfeited thier lives for presuming upon God (Nadab and Abihu, Korah and Dathan, Israelites taking land after bad report, Uzzah, Saul, etc...). Presumption is one of the most dangerous sins one can commit - both physically and spiritually.
Don't forget, people like David and Paul are exceptions to God's rule. People like Uzzah, Nadab and Abihu, et al, these are the rule. The consequences of sin are death (Romans 6:23). God could justly take the life of all men, immediately following sin as punishment of their sin. However, after each one of us sin, He grants clemency to all. Every time we draw breath, we do so in mercy. Our existence, like David and Paul, are the exceptions. Uzzah, Annanias and Sapphira, and the others, demonstrate the rule. The continued existence of every sinner continue to demonstrate God's mercy and clemency - at least for now... Of course, there is coming a day, when the time for mercy will be over and eternal judgment will be meeted out (Acts 17:30-31).