Why is the humanity of Christ important in sovereignty grace theology?

In sovereign grace theology, the humanity of Christ is crucial because it provides the basis for His role as our mediator. He needed to take on human nature to fulfill the law that we could never keep and to experience human suffering. This allows Him to relate to our struggles and temptations while being the perfect sacrifice that fulfills all righteousness. His ability to identify with us means that when we trust in Him, we are united with His perfect obedience and righteousness, which is imputed to us.