I'm not a Jew or Christian. It's not "my Bible". Evangelicals teach and condone all kinds of loony garbage, and those groups often are basically cults . Child marriage was never permitted by Catholicism, Orthodoxy and so on, the main and most ancient Christian bodies.you seem very ignorant of both your bible and history.
They were allowed to marry at 12/13 because that's when they are traditionally considered to be adults in the Jewish community. People are typically going through puberty then. Mary, the mother of Jesus, was likely about 13 or so when she gave birth to him. It was common for people around the world to marry around that age. We didn't live very long then. But that's not the same as marrying a 6 year old.