Jacob Arminius was a Dutch theologian born in 1560, known for his ideas that challenged the strict doctrines of John Calvin. He studied theology and became a pastor, where he began to question the concept of predestination, which suggested that God had already chosen who would be saved. Arminius proposed that humans have free will and can choose to accept or reject God's grace. His beliefs led to the formation of Arminianism, a movement that emphasized God's love and the possibility of salvation for all. This sparked significant debate within the Protestant community, influencing many denominations today.