Wikipedia
Amyraldism (sometimes Amyraldianism) is also known as the School of Saumur, post redemptionism, moderate Calvinism, four-point Calvinism, or hypothetical universalism (though it is in fact one of several hypothetical universalist systems).
It is the belief that God decreed Christ's atonement, prior to his decree of election, for all alike if they believe, but he then elected those whom he will bring to faith in Christ, seeing that none would believe on their own, and thereby preserving the Calvinist doctrine of unconditional election. The efficacy of the atonement remains limited to those who believe.
This doctrine is named after its formulator Moses Amyraut, and is still viewed as a variety of Calvinism in that it maintains the particularity of sovereign grace in the application of the atonement. However, detractors such as B. B. Warfield have termed it "an inconsistent and therefore unstable form of Calvinism."