According to scripture, all believers are saints. So if he confessed Jesus Christ as the son of God and his savior he already is - and you are, or can be, as well!
It says believers are called to become saints. Not that believers are saints.
Think of it as making it into the Hall of Fame, to be an example to the other mere mortal saints. ;^)
First, a person is pronounced "Venerable." Second, a person is pronounced "Blessed", and Third, a person is pronounced a "Saint."
Additional details are in these links -- please educate yourself.
How Many Miracles are Required to Canonize a Saint?
Saints [Catholic, Orthodox, Open]
SAINTHOOD 101: Rules for Becoming a Saint [Catholic Caucus]
The Process of Becoming a Saint (Canonization) [Catholic Caucus]
Pope Lists Criteria for Causes of Canonization
“believers”
This is conveyed in how you live your life, NOT in repeating a sentence from Scripture.
Merely affirming a “belief” and then living your life contrary to what that entails, is no “belief” at all.