Romans 8:29

Romans 8:29. For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.

That was the very end and object of their predestination that they might become like Christ, their great perfect elder Brother.

"’Christ, be my first elect,’ he said,

Then chose our souls in Christ our Head

Before he gave the mountains birth

Or laid foundations for the earth."