How do observant Jews get around the ultra-violent commandments in their holy books?

Answer 1

Observant Jews argue that the evidence requirements to implement the penalties are so steep that it is almost a moratorium. The argument goes as follows. Deuteronomy 19:15 states that two witnesses are necessary for conviction of a crime. The Rabbis understood this to mean that in a capital offense, two witnesses are needed and that, furthermore, the following must occur (1) both witnesses must advise the person BEFORE the commission of the crime that the crime is a capital offense crime, (2) both witnesses must advise the person DURING the commission of the crime that the crime is a capital offense crime, (3) the perpetrator must acknowledge hearing and understanding these admonitions, and (4) the witnesses must not be related and must not have contact with one another during the trial. These are a few of the many requirements.

Example:

Isaac wants to be an idolater and tells his wife Rebecca that he is going to buy an idol and worship it. Rebecca tells him "Idol worship is a capital offense". Isaac says that he knows this and is going to do it anyway. Isaac goes to the store which sells statuettes run by Michael and tells Michael that he is going to buy a statuette to use as an idol. Michael says to him, "Idol worship is a capital offense". Isaac says that he knows this and is going to do it anyway, buying the statuette. Isaac returns home and begins praying to the idol. Michael, suspecting that Isaac will start praying to the idol comes over to the house and yells through the front door that "Idol worship is a capital offense and I see you doing it". Isaac yells back that he knows this and is going to continue anyway. Rebecca then comes home, finding Isaac still praying to the idol. She tells him that "Idol worship is a capital offense and I see you doing it". Isaac responds back that he knows this and is going to continue anyway. The religious police who then enforce the law find Rebecca and Michael and talk to each individually. Each gives testimony in the trial, but at separate times and escorted specifically to prevent them from talking to one another.

Answer 2

The Torah gives authority to the Sanhedrin (Jewish court) to punish certain types of crimes. They are bound by exacting procedure, they must have two witnesses, and the perpetrator must be warned before he sins; otherwise he is not punished by the Sanhedrin. Also, the Sanhedrin is enjoined to make a concerted effort to seek evidence that could exonerate the defendant. This means that they must be balanced and circumspect, no matter what the crime. Their role is not intended to be one of vengeance.
Shortly before the destruction of the Second Temple, the Sanhedrin ceased dealing with capital cases, because the increased persecutions of the Romans, and the onset of the present Exile, made it impossible to fully maintain the level of scholarship and expertise needed for the Torah-procedures of the Sanhedrin. Since then, the power of Jewish courts has been greatly diminished and is now limited to imposing fines, if anything.