Lovelylil
I read the book some years ago. But I felt that the author had certain prejudices (orthodox standards) he used to define what he thought was Christian. For example, the trinity doctrine becomes a litmus test for judging what is or is not Christian. But this doctrine was not developed until the 4th century and remained a controversy within the church for centuries thereafter. Likewise other doctrines such as immortality of the soul and hell are assumed to be scriptural because orthodoxy tells us so. But it should be noted that the orthodox views were only accepted after years of violence and persecution directed against the opposition. In the end many accept orthodoxy because "might makes right." But there are legitimate arguments that should be considered regarding the teachings of early Christianity and the Bible.
Personally, I'm not sure it will be doctrine that will decide God's favor. Humans are judged by their deeds according to the Biblical standard.