Thesis XVIII. Those reborn by Christ's grace remain liable not only to lighter and smaller sins; hardly any of them fail at some time to fall into grave sins. Through these they are held bound by a fresh guilt of eternal death and lose their present fitness for the kingdom of heaven, until God's special grace stirs them and they rise again by a particular repentance.
The frequent falls of the saints recorded in Scripture show this, such as David's, who fell into adultery and murder, and Peter's, who denied Christ three times with an oath. The daily experience of the faithful confirms it all too often.
Latin
XVIII. Neque tantum levioribus & minutis peccatis homines per Christi gratiam regeniti obnoxii manent: sed vix ulli eorum sunt qui non quandoque incidant in gravia peccata; quibus novo mortis aeternae reatu constricti tenentur, & praesentem aptitudinem ad regnum coeleste amittunt, donec speciali Dei gratia excitante, inde per singularem poenitentiam resurgant. Id manifestum faciunt frequentes sanctorum lapsus in Scriptura memorati, ut Davidis, qui incidit in adulterium & homicidium: & Petri, qui ter Christum cum juramento abnegavit. Idemque nimis saepe confirmat quotidiana fidelium experientia.