The best way to answer these questions is to ask some good solid biblical questions back.
For instance, ask the person this question:
According to Romans 8:17, the Apostle Paul states that ... "if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with [him], that we may be also glorified together."
What was it that Christ inherited? And, why would Christ ask the Father for those who follow, preach, and teach would be glorified just as Christ is glorified, and because Christ Glorified the Father in this world? (See John 17).
The whole idea of deification rests upon the person and nature of Christ. Ask them if they believe that God himself came down to be a man? If they said God could not, then ask them why did Christ come down? Is he not God?
If Christ took upon himself mortal flesh and bone, was obedient and subordinate to the will and commandment of the Father (which the numerous New Testament passages definitely attest too), how much more are we to follow the same pattern that Christ himself shown us to follow?