I will assume, based on your reply, that you don't believe in God. Please correct me if you, in fact, prefer one of the other options listed - or another one, which I may have forgotten (e.g.: a cruel God, like some of the ancient Roman or Greek deities).

You got many replies already, but since your post was directed to me, I feel compelled to reply.

As I said before, it is a difficult question - and there are, in theory, many possible answers.

A higher purpose in terrorist attacks? In this particular case, I find it fairly easy to see one. The recent terrorist attacks have helped to weld mankind together. For instance, governments all over the world are starting to cooperate on terrorist issues.

Why did it have to come this way? Couldn't it have been different? I think the answer is yes it could have been. But God has given us lots of opportunities to resolve our problems peacefully - mankind hasn't responded yet. For instance, Bahá'u'lláh - who I believe is the representative of God for this Era - has sent Tablets (letters) to the main governors of the world, towards the end of the 19th century, enjoining them to work together peacefully, reduce armaments, etc. But did they listen? Not yet, not quite. (For related texts, you may be interested in reading "The Promise of World Peace", http://www.bahai.org/article-1-7-0-2.html, a document of ca. 30 pages that was distributed for the International Year of Peace).

Finally, when talking about God's injustice, you may be thinking - although you didn't quite state it - that all the people who died in the mentioned terrorist attacks, ceased to exist the very moment they died. That is not what the opinion of most people who do believe in God. A belief in some sort of afterlife is an essential part to most religions.

Hilmar.