I wouldn't describe the bible as 'fiction' though, BackOnlyBrieflly. I'd describe it as history, as poetry, as prophecy, as recount. As a long emerging understanding of who God is and God's character. As written by a multiplicity of authors over thousands of years, and so if we are to read it we are to read it while understanding something of the where, who, how and why of it.
So one section will describe the passover or Jericho, and another how child sacrifice is repellant to God, and how God is merciful and loving. It is hard to reconcile the God of these passages, with all the mental gymnastics of the world we cannot twist these around. But there are ways in which to gain greater understanding of what they actually meant to the person writing and the people they were written for, which can help us understand and apply them. This doesn't mean we have to a/ agree that God killed babies and that's fine, or b/say it's all a work of fiction/metaphor so it doesn't matter anyway. No. It's our job to grapple with the scriptures and work out what God was saying through them, and use our knowledge of who Jesus is to balance some of the OT passages.
I don't have this all sorted. I don't have neatly packaged answers. Some of it is taken on faith, yes, but that isn't a kind of 'oh it's too big so I'm just going to ignore it lalalala' kind of faith. More a personal experience of who God is and a knowledge of who God is through what Jesus has done which makes me able to come to such passages and say 'hey, I don't know. But I can still grapple, and I can still know God is good.' I do realise this is not enough, I honestly do get this. It wouldn't be for me either, if not for the consuming knowledge of God and the work God does in lives today, and the utter freedom that knowledge and experience brings. How can I reconcile it, how can I balance this all? The answer is, actually, I can't, always. I have questions! I don't squish my intellect in order to justify my faith, but I do have faith anyway, while knowing there are things I am just not going to be able to know or reconcile at this time.
It's not an easy faith to hold, sometimes, no. Hence the doubts referred to earlier. But it's life giving and hopeful and wonderful in its complexity and in its simplicity.