Mourning, just like celebrating, is acknowledging God’s will in our lives. And I agree. It is saying that no matter what happens, He is in charge. And He will make all things work together for good to those who love the Lord. It is a confirmation of Romans 8:34-39, and shows what faith to a believer truly is. No matter what, we know He is in charge and He knows why.
There is a denial of that in too many charismatic circles.
It’s labeled as a spirit, rebuked, something to be “delivered” from, denial that it’s from God, anything but acknowledging that God is in it and God is good, and He’s working out the character of Christ in our lives.