Rome's Challenge: Why Do Protestants Keep Sunday?

It seems many Protestants are becoming much more open to Rome's call to unity with the Catholic Church. Have Protestants forgotten what the protests were about? Has the protest stagnated because of Protestants embracing Sunday as the "Christian" Sabbath, while claiming "The Bible Only" as their authority? Does Rome hold Protestantism in the palm of its hand by virtue of Protestant acceptance of Catholic tradition regarding the change of the Sabbath?

Check out Rome's Challenge for yourself at the following link: http://biblelight.net/chalng.htm