The Untimely Death
I know that it is difficult to understand why a child would be taken from a parent in an untimely manner and I also know that some people are not "extremely religious". With that said, when Adam and Eve "fell" sin entered the world and the curse of death fell upon all people. The natural death of any person (including children) is a consequence of the fall of man and the curse of sin entering the world.
What I mean by that is prior to the fall of man, life was perfect. There was no sin, no deteriorating of the body, no death, and no separation from God. That was how God intended it to be. However, when Adam and Eve ate of the forbidden fruit, they willingly chose to disobey the one rule that God had put into place. Why did they do it? If you look in Genesis, it was because they wanted to be like God. They wanted to be God. They wanted to be the center of their rule. They wanted the final say. I won't go into it all here, but this was not just eating a piece of fruit; it was much more. As a result of their deliberate choice, life forever changed. No longer would Adam and Eve live in "Utopia"; they were kicked out of the garden and had to work hard for the things that had previously come much easier for them. Their bodies began to deteriorate and death became inevitable. They were separated from God.
Now I know that it does not seem fair that because Adam and Eve did something and now everyone else suffers because of it. However, the fact remains that Adam and Eve were the representation of all mankind. Because of that we all are found in them. And quite frankly, no one can say that if they were there in the garden that they would not have made the same choice. God gave mankind the ability to choose and mankind's nature is not that of goodness. We are selfish to the core and given the chance we will do wrong. For example, no one has to teach a child how to lie. It is part of their nature. It is because of this that all men fell out of the grace of God. No one is righteous, not one human being.

I know that this does not console hurt and loss. That is why it is important to look at how Jesus reacted to death when he walked the earth. When his friend Lazarus died, an untimely death, Jesus wept. Remember that when Jesus wept he already knew that he would raise him, Lazarus, from the dead. Mourning when someone dies is natural. It is to be expected. It is a loss. It is difficult. I am not trying to sugar coat that aspect. I am just trying to explain "Why".
I don't know if this made the consequence of that original sin more understandable or not. Either way, I am truly sorry for your co-worker's loss. May it be a comfort to you that God too wept at the loss of that innocent live. God also weeps at the hurt of this couple. He hurts the same way that we do when our own child is hurting and we as parents have to sit by and do the best that we can to console them, yet we cannot take the pain away.
I hope that you know that God is a loving God, who planned for us to live forever in the Garden of Eden. I hope that you know that it is mankind that chose to thwart that plan and wanted to be more than was intended. I hope that you know that it is mankind that brought the consequences of sin, death, and separation from God on all of mankind.

Thank you Anne for posting that comment. I apologize for not getting back to you sooner as not only was my blog under construction, but so was my life. I know we all struggle in understanding the "Why" of terrible things. I guess in closing I just want to say that when it all boils down, the main key is faith. Faith that God has a plan. Faith that God's plan involves providing a way for us to escape the curse of sin and death. Faith to accept that plan. Faith to walk through the ordeals of life, while keeping the focus on the prize at the end, eternal life. May God grant you that faith!