Indeed, the God of the Old Testament is simply not credible as the Father of Christ. The Old Testament is largely bat-sh*t-crazy. Richard Dawkins said it best: 

"The God of the Old Testament is arguably the most unpleasant character in all fiction: jealous and proud of it; a petty, unjust, unforgiving control-freak; a vindictive, bloodthirsty ethnic cleanser; a misogynistic, homophobic, racist, infanticidal, genocidal, filicidal, pestilential, megalomaniacal, sadomasochistic, capriciously malevolent bully."

Christ, whether you believe in his divinity or not, was altogether different, and apart from loving the aforementioned bully, a wonderful model by which we'd all do better to pattern our own lives. Roughly 99.99% of so-called "Christians" don't do that, unfortunately.