"He said to them, 'But who do you say that I am?' And Peter answered and said, 'You are the Christ.'" (Mark 8.29 E.S.V.)
"Before leaving this subject, special attention should be called to the fact that the words of Jesus 'But you, who do you say that I am?' convey a very important lesson, namely, that a true believer is one who is willing, whenever necessary, to express a conviction that is contrary to that of the masses. In the best sense of the term, the believer is willing to come forth boldly in the interest of the truth.
The Kingdom is for vigorous people ...for strong and sturdy men like Joseph ...Moses ...Joshua and Caleb ...Samuel ...David ...Nathan ...Elijah ...Jehoshaphat ...Daniel and his three friends ...Mordecai ...Stephen ...Paul ...Epaphroditus ...Onesiphorus ...and the apostle John ...It is for such valiant women as Ruth ...Deborah ...Abigail ...Esther ...and Lydia.
Conformity with the world, compromise on basic issues, the unwillingness to be distinctive, is strongly condemned in Scripture ...not being 'of the world', believers are shining lights in the midst of the world ...They are spiritually different from the world, in order to be a blessing to the world.
So here in Mark 8.28, 29, while everybody else is saying that Jesus is but a man ...the true follower of Jesus answers 'Thou are the Christ' (thus Mark), 'the Son of the Living God' (adds Matthew).'"
William Hendriksen on Mark 8.27-130