Nor is Uncle Tom an "Uncle Tom." He is a Christ symbol. This pivotal character needs to be understood both in the context of religious nineteenth-century America and Stowe's contrapuntal narrative. In the midst of this very violent book, the religious Uncle Tom is the calm at the eye of the storm: patient, tolerant, unwilling to use violence himself even when--a point conveniently overlooked--he approves of other slaves' decision to stage overt revolt. Uncle Tom encourages George and Eliza to flee. Knowing no other way of life, he chooses to resist the slave system by small acts of kindness and moral persuasion. The vast majority of American slaves would never flee their plantations. Stowe is contrasting two forms of resistance (which in many ways parallel the philosophical differences between Martin Luther King Jr. and Malcolm X): the Bible and the gun.
Quoted from Darryl Lorenzo Wellington's essay. However, this essay will be a spoiler for those who haven't finished the novel.