Why does mainstream Christianity still have such a heretical view of God?

I spent most of my life fearing this idea of an angry, infinitely vindictive god who threatens people with fire if they don’t “love” him. I never understood ECT but once I discovered Universalism everything clicked for me. How come despite the overwhelming evidence supporting Christian Universalism it is still so unpopular? If God doesn’t want anyone to perish but have eternal life then why would he willingly lose most of his creation to his enemy?