These questions are tagged especially to relate to beliefs and doctrines held by, or attributed to, Reformed/Calvinism. An explanation and definition are taken from Wikipedia:
“Calvinism (also called the Reformed tradition or Reformed Protestantism) is a major branch of Protestantism that follows the theological tradition and forms of Christian practice set down by John Calvin and other Reformation-era theologians. It emphasises the sovereignty of God and the authority of the Bible.
Calvinists broke from the Roman Catholic Church in the 16th century. Calvinists differ from Lutherans (another major branch of the Reformation) on the real presence of Christ in the Eucharist, theories of worship, the purpose and meaning of baptism, and the use of God’s law for believers, among other things. The term Calvinism can be misleading, because the religious tradition which it denotes has always been diverse, with a wide range of influences rather than a single founder; however, almost all of them drew heavily from the writings of Augustine of Hippo twelve hundred years prior.”