Good question Jovaro.
God hasn't pre-destined or fixed our every move, thought, action etc ... BUT ... Because he is out of Time and in Eternity ... He KNOWS EVERYTHING we do and all the choices we will make.
He has never fixed our every move, if he did ... This would not be free will. Christianity is not against free will, God does not force us to Obey him or force us to do good, but ... If we did Follow hwat God said, things would be much better in life. Afterall, he's all knowing, he knows whats best for our life, he has a plan and purpose for each one of us.
in Islam, if a person leaves ... They are to be killed. God cannot be God if he does something against Free will. Especially if he tells us to kill those that leave Islam, Gods not like that, i thought the Quran always says "in the name of the most MERCIFUL" ... Merciful my foot. Is that mercy? Is that grace? Is that love? That you should kill those that leave Islam?
God knows our every move, but because he knows something, doesn't mean he planned it that way or fixed things up.
I hope this helps my friend. God Bless.