Isa 46:8-11 “Remember this, and be assured;
Recall it to mind, you transgressors.
9 “Remember the former things long past,
For I am God, and there is no other;
I am God, and there is no one like Me,
10 Declaring the end from the beginning,
And from ancient times things which have not been done,
Saying, ‘My purpose will be established,
And I will accomplish all My good pleasure’;
11 Calling a bird of prey from the east,
The man of My purpose from a far country.
Truly I have spoken; truly I will bring it to pass.
I have planned it, surely I will do it.
12 “Listen to Me, you stubborn-minded…

I will be the first to say that I do not claim to understand how predestination and free will work together but believe they co-exist even though it goes beyond my comprehension now. But so do other things revealed by God – like, John 1:1 In the beginning was the Word, and the Word was with God, and the Word was God. How can that be? I’ll be the first to say I don’t understand everything nor can I explain everything, but neither of those keep me from saying what I think is so.

The Apostle John did the same (John 1:1, 12-13 for examples). The Apostle Paul did this. Compare Romans 9 with Romans 10. Jesus did this. Look at His conversation with Nicodemus in John 3. His speech to Nic is like a gold coin; it has two separate sides to it. On the first side Jesus says very clearly it is not up to you, it is up to God – you must be born from above. Then, Jesus turns the coin over and stresses you must believe – it is up to you. I think the little word “and” in verse 14 (left out of most english translations but present in Greek) is often left out of our thinking. We think either/or. Jesus, Paul, and John though both/and even though it is hard to understand. But we are talking about GOD. I would think if He truly revealed Himself I’d come across things beyond my comprehension.

People, in general, can’t accept this. People react the same way they reacted to Jesus, John, and Paul.

Study John 6 where Jesus speaks very clearly the both/and message. Watch the crowd’s reaction and take note of the disciple’s.

I believe Jesus’ message was explaining the existence of two sides of the SAME coin.

John 6:37-40
“All that the Father gives Me will come to Me,

“AND”

“the one who comes to Me I will certainly not cast out.

He repeats the same thing with more details.

38 “For I have come down from heaven, not to do My own will, but the will of Him who sent Me. 39 “This is the will of Him who sent Me, that of all that He has given Me I lose nothing, but raise it up on the last day.

[AND that is not all there is to the will of God]

40 “For this is [the other side of] the will of My Father, that everyone who beholds the Son and believes in Him will have eternal life, and I Myself will raise him up on the last day.”

I could go on, you can probably tell.
But do you see understand? I hope NOT.

How can you tell if God has given you to His Son? How can you tell if you believe? Follow the advise Jesus gave Nicodemus at the end of his message to him in John 3.