Worshipping God is not about necessity. Life itself is not necessary. Is living even justified ?
Your point here is based on a mere assumption; IF god tells you to kill your family, IF Abraham killed his son. the truth is god would never tell anyone to kill anyone just for the sake of it. God "rules" are not random or meaningless, if they were, then God does not deserve to be worshipped. What happened with Abraham was a test of his faith, Abraham was ,supposedly, in a direct contact with God (or with Gabriel), his situation required him to have more faith than the normal person. It is simply a different situation.
So don't worry, I'm sure no one would ask you to kill your future son or daughter :)