God has absolute power over everything, so God is ultimately the cause of everything.
So even if he “allows” things to happen, those things are ultimately caused by him too.
All the theories aside, the most practical question is whether God is good to those who fear and worship him. This is something each individual has to experience and decide for himself.
The old testament has plenty of examples of the kinds of terrible things God does to those who ignore him. That’s why there’s the expression “fear and trembling”. The biblical God clearly deliberately inflicts harm.
So the basic idea is that those who do _not_ worship God will suffer by God’s hand.
But those who _do_ worship God will also suffer by God’s hand, though in the way a father disciplines his son, i.e. with good intentions. See Proverbs 3:11 and Hebrews 12:5.
The trouble arises when a Christian experiences some ridiculous tragedy, and can’t imagine why a father would do that kind of terrible thing to his son. When such things happen, it is easy for us to imagine a thousand different better ways. In such times, Jesus’s example of suffering is instructive.
Christianity already has a foolproof theory on suffering that makes God look good even when sh*t happens. Because God always knows better, the suffering was for a higher purpose, etc. We just gotta be “humble” and accept everything.
But sometimes, “humility” has its limits. When someone thinks he has worshipped God faithfully, but still experiences something terribly tragic that seems completely uncalled for, he can wonder if Christianity is just a scam after all. Because being “humble” is not so different from being “gullible”.
In such ridiculous situations, maybe it becomes reasonable to ask whether we have misunderstood the real meaning of “omnipotence” (direct translation of the Hebrew and Greek words in the bible means “all powerful”, or “almighty”). If the universe is finite, “universe” being defined as “all that exists”, then “all” power is still limited/finite power, and not quite the “unlimited/infinite” power that theologians have made up. So maybe sometimes bad things happen because it was simply unavoidable in a finite universe.