to let someone go: to set a person loose from a hold, a duty, or a relationship and send them on their way
At its root this verb means to loose someone from something that has held them. The same act looks different depending on who is being let go and from what, so English needs several words for it:
- a prisoner is released
- a crowd is dismissed
- a wife is divorced
- a dying man is allowed to depart
In every case one party has been holding or keeping another, and now lets them go free.
In the Gospels the most frequent setting is Pilate at Jesus' trial, where the governor keeps trying to release a prisoner and the crowd demands Barabbas instead. A second common setting is Jesus sending a crowd home after teaching or feeding them, and the book of Acts uses the same word for officials freeing the apostles from custody.
The sense that carries the most weight is divorce. When a man let his wife go, he sent her out of the marriage and the household, which is why English translations switch to the word "divorce". The legal background is a written certificate that formally severed the bond, the practice Jesus addresses when the religious teachers test him about lawful grounds for sending a wife away.
Two gentler uses round out the range. Simeon asks God to let his servant depart in peace, using the word for a master releasing a servant from duty, here a release from life itself. And Jesus tells a bent-over woman that she has been set free from her sickness, loosing the word from people altogether and applying it to release from an affliction.