But it's simply not that simple.
I've been reading the fifth edition of Alden Thompson's book, Who's Afraid of the Old Testament God. It's a substantive and enjoyable read that I highly recommend. Alden writes,
Wasn't it Jesus who suggested that certain people deserved to have a millstone fastened round their necks and to be drowned in the depths of the sea (Matt. 18:6)? and didn't he openly call some people blind hypocrites, comparing them to an old burial ground, full of dead men's bones (Matt. 23:27-28)? And then there was Peter. For all practical purposes he told Ananias and Sapphira to drop dead (Acts 5:1-11). To add to the stories, Paul told the church at Corinth to deliver one of their brothers to Satan for the destruction of the flesh (1 Cor. 5:13). Finally, we must not forget the book of Revelation: Blood, dragons, pits of fire, and even a God who spews people out of his mouth (Rev. 3:16)Alden's point is clear: it is too simplistic to pit the Old and New Testaments against each other as if they are two separate canons which not only have very little in common, but have completely incompatible views of God. I am certainly not suggesting that these violent texts are not difficult nor perplexing, but they exist in the New Testament as well as the Old. So writing off the latter does not solve the problem. To be sure, the New Testament offers us a fuller revelation, a revelation that finds its climax in Jesus Christ. We Christians read the biblical narrative through a christological lens; and such a lens re-focuses the entire biblical narrative as it points to Jesus. This is not a rejection of the Old Testament. The Old Testament was Jesus' Bible, but the New Testament puts the Old Testament in focus in a fuller and fulfilled light.
So for Christianity's neo-Marcionite cultured despisers, who toss out the Old Testament because the violence and judgment offend their modern sensibilities, if you are going to be consistent, the New Testament has to go as well.
We must not forget that the church has affirmed from the very beginning that the Warrior God of the Old Testament and the Crucified God of the New Testament are one and the same... and we cannot understand the coherence of such a seemingly disparate claim without the entire biblical narrative to guide us.