Final answer:
St. Paul was instrumental in establishing that Christ's salvation was universal, available to all, not just Jews. Martin Luther and John Calvin emphasized salvation through faith and predestination. Early Christians had varied interpretations of Jesus's teachings, but they spread the message of His sacrifice for all humanity's salvation.
Step-by-step explanation:
The question of who really cared about the salvation that Christ provided centers on the belief that Jesus was the messiah who offered redemption not just to the Jews, but to all of humanity. The initial confusion whether salvation was available to non-Jews was clarified by St. Paul, asserting that the gift of salvation was indeed universal. This meant that Romans, Persians, Celts, and anyone else could convert to Christianity and be saved.
Moreover, the development of Christian doctrine saw debates about the role of faith versus works in salvation. Figures like Martin Luther and John Calvin stressed the importance of faith alone and predestination, respectively. These concepts were central to the Protestant Reformation and diverged greatly from the Catholic Church's earlier teachings which blended both faith and good works for one's salvation.
Early Christianity faced many interpretations of Christ's teachings, with some expecting a liberation from political oppression while others, following Paul's teachings, understanding it as a spiritual salvation. The spread of Christianity was facilitated by the apostles, who taught Jesus's lessons far and wide, promoting the idea that Jesus' sacrifice was made for the salvation of all people.