We know it wasn't for altruistic purposes. There was a price to be paid for God's wrath and that was the death of all humankind after Adam and Eve. We started over again from Noah's family and this time God did not put up a negative test such as do not eat from the Tree of Knowledge. He put up John 3:16. You've heard it before. Repent! The end is near John 3:16. This time God put up a positive test. Thus, the death of his Son wasn't just for human's salvation. There was a price to be paid and that was death of all the descendants of Adam and Eve. And thus, it is prophecised that we, too, will all die one day. Humankind just can't make it, i.e. be saved, by themselves.
having a bad day?
After drinking too much some people can remain inebriated well into the next day...