The question of suffering is the one question that all of theological history has yet to have a satisfying answer for. The book of Hiob itself concludes this question with faith being something you decide to have despite suffering, not because there is any good reason for it.
I am not saying it is the only hole to poke at theism, but it is THE hole to poke at.
If suffering is part of gods plan and requires deformed children to be born and immediately die, then someone like Stalin, Mao and Hitler were possibly more helpful in furthering gods plan than any good Christian believer ever will be. They certainly had a larger impact on society, laws, culture, etc. Than mother Theresa.
This should lead to the conclusion that believers should embrace evil doers (whom they're supposed to forgive anyway) even more than those that do good, as they are still pushing gods plan.
So all their percieved enemies and lost sheep are really agents of their very own God doing his bidding more successfully than they ever will.
Though, that argument implies that the only plan god has is death for deformed children. If everything is or could be part of god's plan, then you could be as useful as Hitler or everyone else by simply being you and doing nothing.
The more fundamental question to answer is "how would you completely stop suffering?", which I find impossible without taking away everyone's free will.
What if eradicating suffering means that everyone has to go through equal amount of pain and hardship? Would that stop everyone from complaining or would it make everyone complain? What if preventing a greater suffering requires a lesser, necessary suffering? Would that stop people from complaining about it? What if everyone has to take the consequence of one man's fault in order not to make him suffer?
I think the only way suffering would truly stop is if everyone shared the same goal and had no ability for independent thought.
The more fundamental question to answer is “how would you completely stop suffering?”, which I find impossible without taking away everyone’s free will.
Free will can't exist in a world of an omnipotent and omniscient god, so that is not a good excuse because Christians by default can't have a free will.