Why would learning to read and write cause one to desire freedom?
Speculate also about how a culture based in Christian theology (God took the form of a humble human being) and ethics (Love thy neighbor) could have tolerated and even defended slavery.
And I will respond to the first. Reading and writing opens an entire world of knowledge to us. This world is one in which we are entirely in control. If I cannot read or write, I must depend on others for my information and knowledge. That means that others will control my opinions, because they control what information I can receive. Similarly, if I cannot write, I cannot communicate my thoughts effectively. Also, if others write for me, they may distort my true thoughts and beliefs.
If I can read and write myself however, not only can I control what information I intake, I can communicate my views to the world, without being at the mercy of others. I may discover that what i previously believed is invalid, or what I thought was true may indeed be false. To someone whose freedom is not their own (such as under the condition of slavery), the ability to have that power over any area of their life would be immeasurably valuable. And once someone discovers freedom in any area, there would be no stopping the desire for complete and utter independence.
You're really asking two very different questions here, so I'm not really going to have space to answer both...
I'm going to choose your second question.
I believe that a self-professed Christian society could tolerate/support slavery because there is nothing in Christianity that explicitly forbids hierarchy. Yes, Christ is said to have died for all. Yes, we are called to love our neighbor. But nothing says that we are all equal.
Think of some examples: it is clear that children are not to be treated as the equals of adults. It was clear to people in colonial times (they thought it was clear) that women were not to be treated as the equals of men.
So if God made these natural hierarchies, what's to say that he didn't make a hierarchy of races?
And this idea would have had some support from life -- look at the technological differences between Europe and Africa at that time. You can see how people could interpret that as evidence that whites were superior.
2nd question answer: Christianity, as with many religions, fundamentally preach its believers to do good- in that sense, slavery could have been defended out of religion.
1st question answer: By reading and writing, your thoughts are influenced by what you read and thus what you write. Writing helps to clarify thoughts, which further makes the influence of reading stronger. Often, books have been written to show, contradict, satirize a phenomena of society, which thus leads to a desire for freedom to make things the way things ideally are.
Reading and writing allow a person to write what they would enjoy in a life and they can fantasize about all they would like.
In addtion to my agreeing with egraham 17, Learning to read and write causes a person to become more articulate about the experiences that heor she encounters, and when one person becomes more articulate, his or her mind becomes open to new possibilities of existence outside the circles in which he/she was raised in, and when new possibilities enter a persons mind, naturally the person will want to experience more, and have more freedom to explore. Moreover, as I posted elsewhere, "Writing a narrative is very important for the individual writer and for the audience who reads the writer’s narratives. Writing a narrative allows each individual to explore his or her own inner self and come to some sort of realization of epiphany about his/her life. It is my belief that narratives allow each individual writer to re-live a fragment of his/her past life or past beliefs, which results in a responsible acceptance of that past and move forward with higher character, higher self-esteem, and higher knowledge, as with Fredrick Douglas. After all, literature is one of the only things that we have in this world that attempts to make sense of all the issues in life (e.g. love, loss, war, peace, death, happiness, sadness, birth, marriage, divorce, etc) that we go through, and we do not always understand how to articulate those issues; therefore, writing our own narratives helps us come to terms with various issues, and reading the writer’s work instills new ideas of how to articulate an experience that possibly has been shared between writer and reader." Therefore, we become more free to think outside the box just by seeing the power of words, the power to evoke an emotion.