What does it mean to confess Christ as Lord?
In "Word Focus" Glenn McClure writes:
In the New Testament “confession” is understood as a proclamation (profession), as a confession made openly and publicly. “Confession is a sign of repentance (conversion) and thus a mark of the new life of faith” (D. Furst, Dict. of N.T. Theology). It is also seen that a public confession of sins means that the one who confesses is also being set free from them.“ When someone either places himself on the side of Jesus or separates himself from Him in the sight of those who know him, he makes a decision on which God will act in judgment. The believer is so completely included in fellowship with Jesus that his confession before man . . . is regarded as though it had been made before God’s judgment seat. In such a context ‘confession’ includes not only what a man says but also his obedience which has become visible in his whole life” (Furst in Dict. of N.T. Theology).
Source: Studies in Romans: Adult Teacher's Insights, page 58.