Final answer:
On the day of Pentecost, Peter's life was transformed by the outpouring of the Holy Spirit, leading to his bold proclamation of Jesus and the inclusion of both Jews and Gentiles in the people of God. In his first epistle, Peter teaches about believers being a chosen people, called to live righteous lives and show love.
Step-by-step explanation:
a) On the day of Pentecost, Peter's life was transformed in several significant ways. Firstly, he experienced the outpouring of the Holy Spirit, which enabled him to speak in different languages and perform miraculous signs. This empowered him to boldly proclaim the message of Jesus Christ to a large audience, resulting in about 3,000 people being baptized and joining the early Christian community. Secondly, Peter's faith and understanding of Jesus as the Messiah deepened, and he became a key leader of the early Church. Thirdly, Peter's perspective on who could be part of the people of God expanded to include both Jews and Gentiles, as he witnessed the Holy Spirit being poured out on all believers, regardless of their ethnic background.
b) In his first epistle, Peter teaches about the concept of the people of God. He emphasizes that believers are a chosen people, a royal priesthood, a holy nation, and God's special possession. He highlights the importance of living righteous lives and showing love to one another. Peter encourages believers to stand firm in their faith, even in the face of persecution, and to conduct themselves with humility and respect towards everyone.
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