Why is the idea of being called and chosen important in Christianity?

The doctrinal concept of being called and chosen is central to Reformed theology, emphasizing that salvation is not of human effort but rather a divine initiative. In Romans 8:30, Paul states, 'Moreover, whom he did predestinate, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.' This underscores the flow of God's purpose, showcasing His mercy in actively selecting individuals for salvation. It instills confidence among believers, affirming that their faith rests on God's unchanging purpose and call rather than their own actions.