They fully oppose each other, you can't have it both ways. You only fool yourself when you try
No actually BOTH are biblical when viewed in context and when all scripture is taken into context regardless of you ability to see it or even understand it....
This is what you said....
Some rad like there's a limited predestined number to be saved, while others sound like the whole world will be saved.
The bible makes it clear that Christ is the savior of the WHOLE WORLD and that it is OPEN unto ALL MEN and God would have ALL men be saved and come unto the knowledge of the truth...
IT also states that MANY are called but FEW CHOSEN
It also states that those he calls he justifies, those he justifies he sanctifies
It also states that GOD predetermined before the casting down of the world that ALL who would come to him through Christ WOULD be RECEIVED (CHOSEN) in Christ as full grown sons and that this was done before the casting down of the world...
I can think of a plethora of scripture that proves the concepts that you are not grasping....