With 5 pages of replies that I did not have time to read entirely, I may be reinventing the wheel of comment.
Anyhow, most people have a really bizarre twist and perception of the meaning of "predestinate". I think part of it is because religious and cultural influence fashioned and affected their thinking to convey a meaning on "predestinate" that it does not have.
The "foreknow" part is fairly easy. It's reasonable to accept that God can know in advance. I have no idea how, but so He does.
Many people limit their understanding of "predestinate" to have it mean something like "precontrolled" - "premanipulated" - etc..
As a human, our family has more common sense than that. When my wife married me, we predestinated that we were going to have a 3 bedroom house in 5 years; and we did not even have foreknowledge. But we knew that our family would only get so big, and we didn't want the taxes of a 4 bedroom home, so we preset or determined in advance the limits of our house.
God, with foreknowledge, can predestinate people. If He knows in advance that 1 billion people will believe, then there it's available to decree in advance and set a limit to the size of that spiritual family at 1 billion.
It's done without controlling people's free will.
But the modern term of "destiny" cannot be compared to the old biblical idea of "predestinate".