How can a Christian reject part of the Bible and still call themselves a Christian?

[Tonus]

So you're basically saying life and freewill is a bad deal as that's how what I have explained to you.

In other words, you're misrepresenting me on purpose.

No God gave you life in a physical body and he gave you freewill. The problem of sin is a consequence or byproduct of the existence God gave you in the first place. I don't know how many times I need to repeat this.

So sin is "a by-product of life." Before it was a consequence of free will. Either is problematic, but it'd be good if you could keep your story together.

Genesis is a metaphor for the human condition.

What a lousy writer, then.

The plan is a very good one if you understand it.

It's an incoherent plan that cannot possibly be "understood," a problem you are demonstrating in your increasingly confused attempts to explain it.

We're not infected with anything. We are subject to certain unpleasant things given the nature of what we actually are, death is an example.

And what we actually are, per your claim, is the creation of god. Ergo, if we are sinful by nature, this was god's plan.

You can't avoid physical degeneration through the aging process and death or physical and emotional suffering either but life itself is still a gift. A gift that has a downside but you would rather not have been born at all?

It only has a downside because god programmed it in. Under the scenario you describe, I certainly would rather not have existed, since it means that behind the whole facade is a very nasty and very unpredictable being with the power --and the inclination-- to make my life a literal hell.

The design is 100% perfect, intentional and essentially good.

Only if your standards are set impossibly low.

It's perfectly coherent

No, it isn't, as shown by your inability to make it sound coherent in these last few exchanges.

Sin and death is the consequence of something we want to have.

Only because god made it that way, in order to give value to the sacrifice he could have avoided by not making us that way in the first place.