Can you give me Biblical chapter and verse that says Rebecca was 3 years old?

Have you ever seen a 3 or 4 year old on their own on the desert watering a camel?

Now even going with your logic, assume Rebecca was 3 or 4 years old, which she definitely was not, as a Christian I will spit on Isaac and shame him for being a p****Ile. David killed a man and had sex with his wife, you don't see Christians applauding him for that do you? David or Isaac are not answering example for us to follow. Christ is. Now would you condemn your prophet for having sex with a nine year old? No! You would rather justify it.

A six year old playing with dolls happily married? You are more intelligent than this surely.

Concerning Muhammad ordering the rape of female captives of war,

"It was narrated from Abu Sa'eed Al-Khudri that the Prophet of Allah sent an army to Awtas. They met the enemy, fought them, and prevailed over them. They acquired female prisoners who had husbands among the idolaters. The Muslims felt reluctant to be intimate with them. Then Allah, the Mighty and Sublime revealed:
"Also (forbidden are) women already married, except those (slaves) whom your right hands possess," meaning, this is permissible for you once they have completed their 'Iddah."

Sunan An Nisai 3333