The Prophet instructed him that if he were placed in the same situation again that he should again say what his tormenters demanded of him to save himself. They may even try to draw the convert into behavior condemned by Islam just so that his faith will weaken through sinning. Everyone also has a personal devil to raise doubts and temptations. Another implication of the declaration of faith is that a believer should have an open personality without hidden agendas. People should know who you are and what you stand for.
Life is a struggle between good and evil.
The struggle goes on in each person's heart, but it also goes on between people who align themselves with good, more or less, and people who align themselves with evil, more or less. Each of us needs to try to identify the truth, struggle to live by it and help others to find it and live by it. This doesn't mean that you shove your beliefs down other's throats, but one has a responsibility to share beneficial knowledge with those who don't know.