Let's say we had a group of 500,000 people, all of whom were terminally ill and none of whom were in any way religious. They could be either agnostic or atheist, I suppose, but they definitely would not be the kind of people who would ever pray, asking that God heal them, nor would they solicit the prayers of others on their behalf. Let's assume that they were all close to death and resigned to the fact that the end was near. Now, let's say that these people were split into two groups of 250,000 each. The prayers of all Christians, Muslims and Jews throughout the world were offered up to God, pleading with Him to heal the dying individuals within the first of these two groups. No one, however would pray for anyone in the second group. Within a relatively short period of time (let's say two weeks), every single one of the 250,000 individuals for whom prayers were offered were "miraculously" healed. Without a single exception, all of them were as healthy as they'd been at any time in their lives. On the other hand, during this same period of time, every last one of the 250,000 who had not had anyone pray for them (and had not prayed for themselves) died, as had been expected.
Would these results, if they were exactly as I described them, possibly cause you to re-think you lack of belief in God?