Dr. Martin Luther King, Jr. was able to freely follow the faith of his choice due to the 1st Amendment freedom of religion. This freedom grants individuals the right to practice any religion or no religion at all without interference from the government. It ensures that the government cannot establish an official religion or favor one religion over others.
For Dr. King, this meant that he could practice Christianity and deliver sermons at churches across the country without fear of persecution or restriction from the government. The freedom of religion allowed him to openly express his beliefs, share his message of love, equality, and justice, and inspire others through his faith.
It's important to note that the other freedoms listed, such as freedom of the press, speech, petition, and assembly, are also protected by the 1st Amendment and are essential for a democratic society. However, in this specific case, it was the freedom of religion that enabled Dr. King to freely follow his chosen faith and exercise his religious beliefs.