"I believe in God because he personally revealed himself to me."
The problem with personal revelation is that it cannot be verified independently. The person who received the revelation may exhibit a long-term change in character, or other convincing signs that he or she had some sort of emotional experience, but it is impossible to tell what actually happened.
Furthermore, the revelation never includes information that the recipient could not possibly have known and can be independently verified, such as the time and location at which the next earthquake would occur, or any number of as-yet-unsolved problems in science, or even the meaning of "frontlets" in the Bible (Exodus 13:16).
Another problem with personal revelation is that so many people from other religions experience it too, yet they don't all experience the Christian god. If personal revelation in the case of Christianity is to be believed then one must also believe the Muslim when they say they've had personal revelation of Allah.