But christians doesnt mean that: they (mostly) simply mean that we make our own decisions. That we constains some sort of intelligence that can calculate what to do. That we dont simply play up a prewritten script.
Sure. But that then stops their answer from being relevant to the question 'If God wants me to do such-and-such, why doesn't he make his desire clear to me?'
I have the free will to choose to rob a bank, but the law makes it very clear that this is not permitted, and what the consequences of doing it will be.
I have the free will to choose not to worship God, but God has made the most half arsed attempt imaginable to advise me of his opinion on that choice. The dude's meant to be all knowing and all powerful; He knows what would convince me of the rules, and he has the ability to do whatever that is - and if after all that, I choose to misbehave, then that's on me. He also knows that anyone with half a brain is not going to be impressed with the 500 year old heavily edited writings based on two thousand year old oral traditions from people who thought it was vital to know how hard they were allowed to beat their slaves, but had no thought of writing down rules on washing your hands after tending the sick, wiping your backside, or before eating.
He seems also to have been inexcusably lax in letting people in the Americas, the Far East and Australasia know the rules - why only tell a bunch of guys in the Middle East, and not let everyone in the world in on the rules?
Informed decisions need information, and that information is not provided to the vast majority of the world's population. So for us, free will includes freedom from punishment for breaking rules that were never made clear.