However while Jesus did die on the cross to save people in reality Jesus died for all sins.
Now if your theory is true, are you telling me that Christ died for the sins of Satan?
What you are doing here is diminishing God's grace, His sovereignty. You're also saying that Christ could not complete His work. You are doing this by saying that the work must be completed (finished) by man. In reality, John 6 tells us that it is the Father who gives us the belief that we need to come to His Son.
What is your explanation of John 6:65?
Here is what John MacArthur says about the verse.
Although men and women are commanded to believe and will be held accountable for unbelief,
genuine faith is never exclusively a matter of human decision. Once again, in the face of unbelief, Jesus reiterated God’s sovereignty involved in selection for salvation.
John 6:45 tells us that no one can resist the Fathers call. (Therefore
everyone who has heard and learned from the Father comes to Me)
John 10
:11 "I am the good shepherd ; the good shepherd lays down His life for the sheep. 12 "He who is a hired hand, and not a shepherd, who is not the owner of the sheep, sees the wolf coming, and leaves the sheep and flees, and the wolf snatches them and scatters them. 13 "He flees because he is a hired hand and is not concerned about the sheep. 14 "I am the good shepherd, and I know My own and My own know Me, 15 even as the Father knows Me and I know the Father ; and I lay down My life for the sheep. 16 "I have other sheep, which are not of this fold ; I must bring them also, and they will hear My voice ; and they will become one flock with one shepherd.
A Shepherd does not die for another man's sheep. Are there two herds of sheep that we are talking about? Of course let's go back and look at the beginning.
Gen 3:15 And I will put enmity Between you and the woman, And between your seed and her seed ; He shall bruise you on the head, And you shall bruise him on the heel."
Do you think this makes God unmerciful? Paul discuss this in Romans 9.
Rom 9:18 So then He has mercy on whom He desires, and He hardens whom He desires. 19 You will say to me then, "Why does He still find fault ? For who resists His will ?" 20 On the contrary, who are you, O man, who answers back to God ? The thing molded will not say to the molder, "Why did you make me like this," will it? 21 Or does not the potter have a right over the clay, to make from the same lump one vessel for honorable use and another for common use ? 22 What if God, although willing to demonstrate His wrath and to make His power known, endured with much patience vessels of wrath prepared for destruction ? 23 And He did so to make known the riches of His glory upon vessels of mercy, which He prepared beforehand for glory,
You say this is not about salvation, but does not salvation come from the forgiveness of sins? And if Christ died for all sins then are not all sins forgiven?
Even from the old testament the blood did not cover all, only His people.
Ezekiel 45:19 "The priest shall take some of the blood from the sin offering and put it on the door posts of the house, on the four corners of the ledge of the altar and on the posts of the gate of the inner court.
Christ blood covers all sin (all of the elects sins)
1 John 1:7 but if we walk in the Light as He Himself is in the Light, we have fellowship with one another, and the blood of Jesus His Son cleanses
us from all sin.