It’s no mystery. That is just a cope out to support a theology which scripture does not support. The bible states multiple times across those who believe will be saved. It does not save those select who believe.i do not think that God's sovereign purpose in having mercy on who He will necessarily means He creates anyone for the sole purpose of sending them to hell. Everyone is already on their way there; the real mystery is why He shows compassion to any of us
“For I am not ashamed of the gospel, because it is the power of God that brings salvation to everyone who believes: first to the Jew, then to the Gentile. For in the gospel the righteousness of God is revealed—a righteousness that is by faith from first to last, just as it is written: “The righteous will live by faith.””
Romans 1:16-17 NIV
Based on your theology isn’t prayer pointless? Why are we told to pray if its all preset?
God bless