Quran vs. Hadith

How do Muslims justify their Prophet supposedly marrying a 9-year-old girl?

So, I am someone who likes using logic and I have defended Islam and my Muslim-ness many times from criticisms, some well-founded, others not so much. How can I defend Mohammad's marriage to a young girl? He was old at the time. I can't imagine being a child and being given away to an older man. Why did he think that was okay? How do you defend that without sounding like a pedophile apologist? -It is an honest question. How do other Muslims deal with this and remain moral?

The current theory is that Aisha’s young age was invented to defend her against the claims of the hypocrites and some of the Shia that she was an adulteress or unworthy of the Prophet, . By saying she was 9, they wanted to exaggerate her quality as a virgin. From Wikipedia:

Some traditional sources disagree. Ibn Hisham wrote in his biography of Muhammad that she may have been ten years old at the consummation. Ibn Khallikan, as well as Ibn Sa’d al-Baghdadi citing Hisham ibn Urwah, record that she was nine years old at marriage, and twelve at consummation. Modern author and journalist Sadakat Kadri points out that the recording of Aisha’s age by Ibn Sa’d and Bukhari (though the hadith was Sahih) came a couple of centuries after the Prophet’s death. Child marriage was not uncommon in many places at the time, Arabia included. It often served political purposes, and Aisha’s marriage to Muhammad would have had a political connotation.

Muslim authors who calculate Aisha’s age based on the more detailed information available about her sister Asma estimate that she was over thirteen and perhaps between seventeen and nineteen at the time of her marriage. Muhammad Niknam Arabshahi, an Iranian Islamic scholar and historian, has considered six different approaches to determining Aisha’s age and concluded that she was engaged in her late teens. Using the age of Fatimah as a reference point, the Lahore Ahmadiyya Movement scholar Muhammad Ali has estimated that Aisha was over ten years old at the time of marriage and over fifteen at the time of its consummation.

From a historical perspective, it seems highly unlikely for Aisha to have consummated her marriage at the age of 9. Given the immense incentive for later Muslims to reduce her age at the time of marriage (to prove her virginity), the “9″ figure is extremely doubtful and almost certainly a fabrication.

For a deep discussion of this topic, please see professor Jonathan Brown’s Misquoting Muhammad. He says:

Several prominent Sunni ulama today, like Ali Gomaa1 and Taha Jabir Alwani, have concluded that Aisha was in her late teens based on arguments similar to ‘Aqqad’s.

While some Muslims live under the mistaken assumption that Sahih Bukhari and Muslim are 100% reliable, recent research continues to poke holes into this view. Nothing in Sahih Bukhari and Muslim is guaranteed to be 100% correct, only the Quran has this guarantee. The status of Sahih Bukhari and Muslim as unquestionable texts only came about in the past few centuries as scholars tried to defend Islam against Western attacks. The scholars before them have had a more balanced approach to Bukhari and Muslim, as is explained in Misquoting Muhammad.

Everything in Sahih Bukhari (and other collections) must be judged by the Quran, by common sense and by our historical knowledge. Since what it says regarding Aisha’s age is questionable and contradicts other evidence, we are fully entitled to doubt it.