Let's say tomorrow you wake up to find that indeed, an almighty power DOES exist, and said power has provided evidence overnight to the entire earth of its existence. It's all over the news, it's doing interviews, it's demonstrating its powers, it's explaining the meaning of life, etc. etc. In short, there is literally no way to deny its existence. There's one problem though: it's some god OTHER than the one your grew up worshiping. To use the Christian example, it's definitely not Jesus or the holy spirit or god or the ultimate truth, it's absolutely something or someone different. Good thing for you, though, this deity is granting amnesty from retribution for not believing in it, for a limited time! It knows it could have communicated better, or been more present, but the long and short of it is that he doesn't blame you. He does, however, demand that you present yourself to him within 48 hours, bend the knee and renounce your old belief. You can do it and enjoy his good graces, or you can deny it, and be sent to some equivalent of the punishment you used to fear from your old religion.
Would Christians then immediately renounce Jesus? Muslims Allah? Hindus their pantheon? Etc. Etc. Etc. Remember now, this is unquestionable evidence. There's no doubt this thing exists.