Regardless of your religious beliefs, you should never tell a mourning mother that it was "God's plan." For some people, that can be worse than saying nothing at all. For a non-believer, the words that are meant to console a religious person can do quite the opposite.

I choose to believe that my father is still alive, that he has survived death, outlived us all, and possesses the soul that goes on and lives forever; We just cannot see him yet, for we have not caught up with him. our time will come just as his did. and no matter how woeful and lost I was when he passed away, I know I will be glad to go to a place where I can see him, and know he is okay and happy. It’s just not my time yet and there is no way of knowing if any of it is true." - Jane Adams