One Calvinist doctrine teaches that Christ’s work is limited to some people. The “L” in their TULIP acronym stands for limited atonement.
Calvinists are not dispensationalists, and so it is easy to understand their conclusion if Prophecy and Mystery are confused.
In one part of the Bible salvation is offered to the “many”, but now it is offered freely to “all”.
In Prophecy, salvation was promised to one nation, an elect, representing only a few people on the earth. Christ came only to them (Matt 15:24; John 1:11).
“Even as the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many.” – Matthew 20:28
Jesus’ ministry to the circumcision was to confirm prophecy and promises to Israel (Rom 15:8; John 4:22).
When Jesus later revealed the mystery of the gospel to Paul, he explained how grace could now be offered to all without Israel (Rom 11:32). What was once limited was now offered without exclusion.
“[Christ Jesus] gave himself a ransom for all, to be testified in due time.” – 1 Tim 2:6
What was once limited to many, has now been sent to all. This is one difference between Prophecy and Mystery. It helps to dissolve the controversy with Calvinism.
It can also help with Hebrews. Hebrews speaks of the ransom to many (Israel), while Paul speaks of the ransom to all.
The confused confrontation continues between Calvinists and Arminians, but the issue can be simplified and solved by rightly dividing Prophecy from Mystery.