Kieran, the problem with free will as has been stated before is that it is a localized phenomena.
Meaning that each individual might have free will, might have the possibility to choose between A and B, but on the grander scale, there is knowledge of exactly what said individual will choose.
So God gave us free will. Even before he did this, even before we were created, he knew exactly what our choices would be.
When a path is known, a random element such as free will is by and large eliminated in the grander perspective.
It's akin to having a computer program where you have a randomizer and depending on what it outputs, A or B is chosen. Now, nothing is random in a computer (there are however various ways of getting a quite random number) and if the conditions are the same each time the program is run, the outcome will be exactly the same. Gods knowledge of us is similar to such a program.
After all, he set the conditions, he created the algorithm. And still he chooses to punish some for just following the algorithm. Or nbot punish; modern Christians are likely to argue that God isn't punishing; it is man who removes himself from God, not the other way around.
On the other hand, that argument is just a play on semantics. If I say 'either you wash my shoes or I'll kill your entire family and rape your dog, or you'll be moving away from me' you probably wouldn't accept it as you removing yourself from me - rather the conditions I've created are so harsh that it's me who is unfair.
In the free will situation there's the added problem that your future actions and the outcome is known to God.
I like you xample 'god makes it possible for you to jump. God makes you decide whether to do it or not. But he dinnae make you'. It shows the essential bit here and what's very easy to get wrong. But perhaps it is prudent to add 'God has set the conditions so that you'll jump, but outta free will' - this would more precisely reflect the situation.
Free will is a very tough philosophical question - and not even unique for Christianity. So we're not talking strictly Christianity here but a question spanning a much wider area. It is certainly interesting to get the Christian explanation however. Looking forward to more replies and I hope we can have a civil discussion without hidden remarks/contempt.