There are many verses in the Bible that make at least one fact clear: God chooses whom He shall save. Not me, not thee. Our free will? We exercise it, yes, but our mightiest efforts can not change that which God has ordained.
A very strong example, from John the Evangelist, my namesake, verse 6:44:
No one can come to me unless the Father who sent me draws him.
This is our Lord speaking, mind you. Now, one might dispute the accuracy of this portion of the Word. But not its meaning.
Which cuts to the heart of the matter for Christians who profess to be Bible-believing: Much of Scripture is allegorical, and has layers, and some of those are hidden from a simple reading of the text. Yet, this particular verse, and others like it, is crystal clear: God chooses; God is sovereign; God calls those whom He would.