Ultimately, the realisation of God's existence will surely come when our spiritual soul no longer sees things through human eyes. Then we may come to accept the reality of God's creative power, and discover the reason why we have been given the amazing gift of free will. And we then ask ourselves the question: How well did we use this gift?
Pure conjecture on your part, Alan, but, for the purposes of my response, I'll go along with what you say:
If you are indeed correct then my attitude would be quite clear. I would have tried to use this 'gift' of free will in keeping with my own values. Of course, I might well have failed at times, just as anyone(Christian or non Christian) might, but as long as I have used this 'gift' sincerely, then I would expect to be judged by your God in a fair and equitable manner, and certainly not based upon an unfair selection process of whether I was a Christian or not.
Your idea that at some point later we may discover that your God actually exists, and that we will then discover the reason why we have been given this 'amazing gift', can have no bearing whatever on what I have just said.