Did the people who decided to follow the Harold Camping cult, renounce their faith in Christ?

There's no way to know if the people who follow Harold Camping's prediction have renounced their faith. To know that, you would have to judge their hearts and that is also unbiblical. These people who are predicting May 21 as Judgement Day are not evil people - they're misguided. It tends to be what happens to people when they leave their churches (as Harold Camping believes everyone should do), have no accountability and persue whatever their itching ears want to hear. A group of people (now called the Mormons) did the same thing when they decided to follow Joseph Smith instead of the Bible. That's what happens when people put their faith in a person instead of God and His Word.