Three problems with this thread here:
1. You say "Does God exist?" but you appear to only be referring to the Christian God (and thus analyzing God only from a New/Old Testament perspective).
This makes for a confusing discussion as some people are giving their 2c on the question as it is ("Does God exist?"
whereas others are debating from a "Does the
Christian God exist?" perspective.
This is an important thing to clarify, because people's interpretation of God/s can vary wildly from religion to religion or as a general philosophical construct etc.
2. Even if the title of the thread was changed to "Does the Christian God exist?", that is still problematic, because Christianity (like most religions) is no singular religion. More like, it is a collective of different sub-religions (Catholicism, Church of England, Protestantism etc) who all arguably have quite differing perspectives on what kind of God they're actually following (and how best to follow him).
Ways to follow Christianity are extremely diverse (and range from the ultra liberal to the ultra conservative). For some, the Old Testament simply exists as a Jewish context backdrop to the religion that Jesus Christ worked to change (and that it's the New Testament which is the book that Christians should focus on). But for others, the Old Testament is considered very much Christianity (not Judaism) and something to be taken just as seriously as the New Testament (with things like the 10 commandments and the story of Creation being just as important to believe in and follow as lessons like Jesus's story of The Good Samaritan).
Etc.
3. So this results in the third issue: What exactly do Christians believe in?
Because most people who follow Christianity, do not follow it 100%/believe in all of it literally. Explanations for the less 21st century appealing aspects of the bible are extremely diverse.
Personally I think that if you take the Christian God as depicted in Old Testament literally, then yes, you do end up with a rather genocidal and unsavory character. But as someone who is not Christian, trying to figure my moral compass around what's written in the bible, is not such a big deal for me.
But since religion affects me regardless, I still think we should try to understand other people's perspectives on the matter, which should be less about whether people believe in God or not (and more about what they believe about following God).
From my personal experience: Most Christians in England, do not pay roo much heed to what's written in the Old Testament. Most of the focus is on the New Testament, which is arguably what Christianity (A.K.A the teachings of Jesus Christ) is really about. And I think we can all agree that most of what Jesus Christ taught, its pretty agreeable stuff (even from a 21st century perspective). Even I (who am not Christian), believe that Jesus was absolutely spot on about some things.
In America though, I've noticed that there are much greater numbers of people who follow more Old Testament-style ways of following Christianity. But I think the times are changing (with a general trend towards much more liberal style spirituality).
Personally I think that religion has a place in society (and that when it leans towards the much more liberal end of perspectives, it generally causes no real issues in society). So what we need to do is to try and encourage and be more accommodating towards liberal religious folks (as opposed to trying to judge and attack anyone who simply happens to believe in a God).
The real question is not whether people believe in a God or not, but what their interpretation of the God they believe in is (which in practice, is almost never actually the literal God portrayed in all of the religious texts).
Ironically, you cannot actually sum up/understand well anyone's belief's simply by knowing the name of their religion. This is a major mistake that many people make (and often leads to the worst sort of ignorance, political decisions, condescending opinions and social divisions).