Being ordered to Kill your son is Evil. That order causes agony , fear and sorrow to a father mad enough or weak enough that he has to think about sacrificing what is sacred to him to a Superior foreign entity. Whether the bastard will proceed to kill him or not doesn't invalidate the pain the order itself causes.
Of course carrying out such an order would be extremely difficult, but again, if God is speaking to you and has convinced you of His existence, then it's not as though some religious official is issuing the same order and claiming it's source is God.
The way you describe the situation, you seem to hold that there is no afterlife as given, meaning that the death of the son means the disappearance of his soul.
We're talking about this story from a scriptural point of view. This means that we take the assumption as given that God exists and that this child will have a place in the afterlife.
God is either insecure and dumb or likes to cause suffering for fun. Sadism.
Not at all, that's a completely outrageous interpretation. God doesn't ask Abraham do to this because he wants Abraham to suffer, instead, the purpose is to test his faith and see how deep his trust (and submission) is.
Recall that in the end, the innocent child wasn't killed, instead he was spared at the moment when it was obvious that Abraham was completely willing to do this.
Muslims for example believe that everything we possess is due to the mercy of God. Therefore, should He choose to take it away, we must be prepared to relinquish it. The same applies to children or family members, of course Muslims would be saddened and in mourning, but they acknowledge that "this life" is transitory and that no one, no matter how healthy will live forever.
Sorry but eternal damnation , a cataclysm that destroys all humanity that is God's creation is also very evil. That God seriously is such a sadistic freak. Thank God that he isn't real.
Again, you assume that God does these things (ie: Day of Judgement) to harm and cause pain to people. If God takes a life, and that person was good, they will end up in paradise.
If this life is a test, as Muslims understand it to be, then ending such a test and permitting a person to spend eternity in paradise is a great mercy.
Imagine for a second that paradise does exist, and that if your time there is infinite, any amount of time spent on Earth will seem unbelievably short. Any trials or suffering you endured on Earth are quickly overshadowed.