For men are not cast off by the Lord forever.
Though he brings grief, he will show compassion,
So great is his unfailing love.
If the "grief" described here is the sufferings of sin and death in this life, how then will God show compassion if most are doomed to torment for all time as a result of those very things? Not only does that make no sense, but it completely contradicts the prior sentence which says for men are not cast off by the Lord forever! No evil that will ever exist, is outside the power and purpose of God almighty...not even "Hell". 1 Samuel 2:6 is a great example,
The Lord kills and makes alive; He brings down to Sheol [translated as "Hell" often] and brings up
This verse could be interpreted like this(according to my theology): God may allow death, but he will make those people alive again. God may allow people to go to "Hell", but will bring them up from it as well. I think this fits quite nicely with my belief, that all humanity is eventually saved unto God. Because if the result of evil is ultimately and completely overcome by God for his glory and to mans benefit(as I believe), than Gods allowance of evil and the devil is of no moral compromise to me. Its like when a child does something wrong, like touching a hot stove for the first time, even after their father told them not to. The parent may have watched it happen, but only does so, because they know that it will only temporarily harm the child and that the child will learn what not to do because of it. Such I believe is a similar reason(though much more complex and varied), for why God allows evil and its griefs in this life. We can run from sunset to sunset searching for thrills that will only bring us down and cause us destruction, but God allows it knowing that we must (and will) come to understand our need for the perfect thrill, the perfect high that is found only within His presence. From the very moment he called us into existence, he knew all that we would do and all the destruction that would result from it...yet allowed it because the end result would be a loving and lasting relationship with all of His creations.
That is the God I serve and love