Of course, you have the option of discounting the Bible's story - relegating it to a fraud and choosing only to relate to a concept-based god who fits your values. But you can't claim that god to be the God of the Jewish or Catholic or Muslim etc., religions. It's nothing more than your own creation.
- Why should it matter if He is cruel? He's God! He created the universe and certainly has the right to run it in any manner He chooses! It's actually quite common these days for people to express personal preferences for God: "I'd like Him to be like this or that or I'd like Him to be a Her" etc., - but isn't that a bit like us creating God in our own image. What possible good is a self-created god? Can something that's no more than the product of our own handiwork or imagination answer our prayers, better the world or eliminate suffering?
- Who are we to decide what's cruel or inexcusable? Do we have a monopoly on morality that we can confidently stand in judgment even of a community or individual human being, let alone the all-seeing and all-powerful Master of creation? (see Isaiah 55; 8 - you might also like to see my essay on the subject).
- Even if it could be demonstrated that the "God of the Old Testament" is unnecessarily cruel and that of the New Testament, kind and just (on the assumption that either or both of these can actually be proven), it might still be worthwhile comparing their real-world implications. For the past decade I've been teaching, among other subjects, Jewish history, and, off-hand, I can't remember a single 45 minute class whose subject didn't in some way touch on the violence, cruelty and horror perpetrated by the disciples of the New Testament's god of love and kindness. With the Catholic church as leader, these past two millennia have been witness to history's most unspeakable terror - more often than not directed against our people. Remember, for example, the murderous crusades? The Cossack massacres of 1648-9? Medieval expulsions and blood libels? Eastern Europe's pogroms? Christian Europe's Holocaust etc., etc.,? I'll take my chances with the people of a vengeful and cruel God any day (the Pope's apologies notwithstanding)!
For more reading, you might try the web site of the counter-missionary organization, www.jewsforjudaism.org. The Ohr Someach yeshiva, in general, is also a wonderful source of information - though you'll have to dig deeply into their archives to find all their terrific material.