Three kinds of confession are necessary for salvation.
First, the confession of one's own iniquity: I said: I will confess my transgressions to the Lord (Ps 32:5), which is the confession of the repentant. The second is that by which a man confesses the goodness of God mercifully bestowing his benefits: sing to the Lord a new song, for he has done marvelous things (Ps 98:11), and this is the confession of one giving thanks. The third is the confession of divine truth: everyone who confesses me before men, I will also confess before my Father who is in heaven (Matt 10:32), and this is the confession of the believer....
[St. Thomas Aquinas, Commentary on the Letter of St. Paul to the Romans, The Aquinas Institute for the Study of Sacred Doctrine (Lander, WY: 2012), p. 284]
