What do I say to my daughter who is fast becoming a non-believer?

I started taking my daughter, who is now 16, to church from when she was 3 years old. She loved Sunday School and was very proud of her drawings of Jesus. She especially loved the last part of the service when children were called up to bang on musical instruments when the last hymn of the service was sung. 

At the age of 12 she was asked to be a server and quickly learned how to help the Clergy out with communion. On special days such as Maundy Thursday or Christmas service my daughter was often the church's first choice as helper because she knew exactly what to do and, more importantly, was able to show the other young servers what needed doing. 

Last year my daughter started studying religious studies and now she is fast becoming a non-believer. Religious studies compels students to think about the concepts of good and evil by using ethics and philosophy as the lens through which to view God. 

She started to question why God was 'allowing' great tragedies to occur and as the tragedies continue to happen around the world the level of her faith is quickly decreasing too. 

I  am not regretful that she is studying religious studies but I do wish that I knew what the right answer was every time she questions my faith. 'Why do you believe in God? Look at what he allows," she says when news of children being killed by ISIS or such like is reported. Sometimes I too wonder why God allows these things. I know about the argument that God does not interfere with free will but it seems inane in the face of misery and outright tragedy.