Durer most probably began the process of working on these initially under the influence of Martin Schongauer.  However, as the work progressed and carried on for an extended period of time, he gradually turned away from the traditional depiction of the ascetic Christ of the Middle ages, and instead was inspired by the classical human form of the antiquity.  According to Ludecke, this image of Christ, projecting earthly strength and beauty “became the guiding light in the peoples’ struggle for the promise of truth and freedom in the message of the Gospel”.  
Kuno Mittelstadt: Durer, Berlin, 1979.8 p.