Good exists - a Catholic comments

[Barry]

There are so many kinds of Christians out there, probably there are some who make a claim like this. 
I think you'll find that no serious theologian after Plato claims anything like this, though. Plotinus, Augustine, Thomas Aquinas, all the way up through Boehme and Blake, would find that image of God to be insupportable and laughable. 
(And by "serious theologian" I mean someone who doesn't ask for money on TV.)

Why are ther many kinds?

That doesn’t make sense since there’s supposed to be only one god and one instruction book

Hi H
You are correct to a degree. There is only one God, and the main instruction book is the Bible. But Jesus Christ also founded the Catholic Church, the one, true Church, and gave it authority to teach humankind. 
Cheers Barry