From Did God Allow the Paris Attacks:
The uncomfortable truth is that most theologians and Christians today and throughout history have said God permits genuine evil. God allows pointless suffering. And they appeal to mystery when asked questions like, “Did God allow the Paris attacks?” They say, “Don’t ask me, I’m not God!”
By contrast, I think theologians and Christians in general need to rethink God’s power. This means rethinking what it means to say God can control creatures and creation, whether these existing things have freedom or not.
In my new book, I’ve carefully laid out an argument that says God’s uncontrolling love prevents God from being able to stop genuine evil unilaterally. God is still almighty, I argue. God is omnipresent and loving too. God knows everything that can be known. But the uncontrolling God I describe should not be blamed for tragedies like those in Paris, because God cannot stop them acting alone.
God is Open 
You conclusion that “God cannot stop them acting alone” is just wrong. Yes, he certainly could have stopped the attack. As Jesus said:
“Or do you think I cannot appeal to My Father, and He will at once put at My disposal more than twelve legions of angels?”
Jesus could have stopped the crucifixion, He even prayed to God for the cup to pass, if possible, but He chose to accept God’s will.
When God allowed the Cross, He had a greater purpose.
In my opinion, the only way to understand why God allows evil to exist in this world, in fact to flourish in this world, is to believe that God has a great purpose. A purpose that in the end will result in greater good. As Paul told us, “For I consider that the sufferings of this present time are not worthy to be compared with the glory that is to be revealed to us.” Romans 8:18
I do not agree with Oord in that God “couldn’t” stop the attacks. This blog quotes the spectrum of Open Theist beliefs.
I do not agree either with the “greater purpose” argument. The logical arguments have been quoted here. Can God not accomplish His greater purposes without evil?
Myself, I take the NT Wright view (and the David Clines on Job view) that God is not the CEO of the universe, meticulously controlling all things. There is no inherent retributive justice in what God designed, nor need there be.
I believe that the “Greater Good” explanation holds up to close scrutiny. Even the detractors of Alvin Plantinga agree that his solution to the logical problem of evil is logically consistent.
When we see what appears to be great evil, the explanation for why God allows it appears to be that God has a bigger plan for “geater good”.
Consider, for instance, the Scriptural answer for why God ordered the Israelites to totally wipe out the entire populations of certain ancient nations “..it is because of the wickedness of these nations..” (Deut. 9:4)
And consider the Scriptural reason why God punishes “…that He might humble you and that He might test you, to do good for you in the end.” (Deut. *:16)
I think it is a mistake to generalize from a specific example. It does not seem all “evil” is meant for a greater good. Jesus seems to think that the Tower of Siloam incident is happenstance.
I think we may be saying much the same thing. I do not think the purpose of evil is to bring about a greater good. As Paul said “Are we to continue in sin that grace might increase? May it never be!” Over and over, Old Testament and New, we are told to quit sinning.
God’s original intention, it seems to me, was for Adam and Eve to not sin. Evidently, they were capable of living their lives sin free, like Jesus. However, they did sin (it was sex before it was time, don’t you think?) and that somehow brought on the avalanche of sin. The end result, though, will be even better than if they had not sinned.
And, no I do not understand that. And, it is very difficult to accept evil when it hits us personally in the face.
I don’t see it as sex. Why would it be wrong for them to have sex?
Gen 4:1 details a sexual encounter. You would think the language would be parallel.
And Paul seems to affirm the entire deceit narrative: 1Ti 2:14 and Adam was not deceived, but the woman was deceived and became a transgressor.
This is all besides the narrative language of the text which suggests the face value understanding.