I would argue that the main similarity between these two characters is based on the way that both either see themselves or recognise that they are passive characters to a certain extent, and that their fate is subject to the interference, machinations and manipulations of others.
Thomas Becket is the classic example of this. Having opposed King Henry because of his plans to try and make the church serve the state rather than giving its ultimate allegiance to God, he returns from France and is warned that he might be killed. However, again and again, Thomas Becket responds to such warnings through claiming faith in a power that is "higher than I or the King." A key quote that seems to indicate his passive nature and his belief in an omnipotent God that controls such matters as whether he dies or not is as follows:
The fool, fixed in his folly, may think
He can turn the wheel on which he turns.
He leaves his fate in the hand of a higher authority, thus showing his passive nature and the way that he leaves himself open to the influence of others rather than seeking to seize his destiny in his own hands.
In the same way, Michael Berg shows himself to be a passive character in the manner that he is scarred and abused as a tender adolescent by Hannah. The way in which he tries to repress the experience and deliberately block out various aspects of the relationship is hinted at later on in the novel when he recalls that he can't remember significant sections of their relationship. He again is shown to be powerless and open to the intentions and influence of another person more powerful than him. Swept up in this feeling, he lets Hannah direct him and is left feeling abandoned and abused at the relationship's close. Of course, this relationship is meant to parallel the relationship of the German people to the Third Reich, and the way that so many were swept up in a feeling of nationalistic ardour thanks to its beliefs and principles, but were left feelings used and guilty in the long term.