In this model Christ did ALL of salvation for PART of mankind.
Based on this, when Jesus died on the cross he only paid for the sins of PART of mankind. Yet he did ALL of the work so that the chosen individuals simply trust that Jesus has completely saved them.
For example if Mother Teresa is not within the part of mankind that Jesus forgave, then she will not be saved from eternal damnation in the end, regardless of any condition she tries to meet. However, if Hitler is within the part of mankind that Jesus forgave, then he will be unconditionally saved from eternal damnation to eternal life in the end regardless of his great sins.
Thankfully, this view also disagrees with I John 2:1-2. It does agree with Ephesians 2:8-9, however. Classic Calvinism fits the description of the ALL-for-PART salvation model.
A verse that suggests this view might be Romans 9:6 (WEB), which could be understood to imply that God has only chosen a subset of mankind. "But it is not as though the word of God has come to nothing. For they are not all Israel that are of Israel."
One should also note that the definition of "faith" used by Calvinist Christians differs radically from the definition used by Arminian Christians. For Calvinists, Jesus has paid the price for salvation and applied it to your account. It is guaranteed. We are simply invited to "trust" in his finished work. It is like a million dollars already deposited into your bank account by your father. Believing does not deposit the million dollars into your bank account, because it is already there! Instead, believing simply changes your life and attitude toward your father.
For Arminians, Jesus has paid the price for salvation, but it is not yet deposited into your account. We must meet the condition of trusting in his work through our free will. It is like a million dollars offered, but not yet deposited, into your bank account. In this case, belief is the condition needed to receive the million dollars so you can deposit it in your account yourself. Otherwise the money is not even there!
This illustration may not be perfect, but it at least illustrates the difference between Arminian and Calvinistic "faith."