Is man the act of God?

Is the father responsible for the son?
Is the father fully responsible for all the acts and consequences?
Can and how a father disown a son?

Maybe, but God is dead now so I think it’s hard to be responsible when you’re dead.

You have it backwards. Man is the father of god, not vice versa.

We created him, then used him to justify all manners of stupidity.

If you would change that to “is the father responsible for the sons decisions” then I could answer NO confidently. In addition a (human) father can disown a son but it is more likely that the son disowns the father by refusing his council and wisdom. God does not disown people, people disown God.