The Catechism in Questions & Answers

576. Will human beings still sin during this time?

Yes. Even though Satan has been deprived of his power and can no longer tempt anyone to sin, human beings will remain sinners and continue to be mortal, since the inclination to sin has not been lifted. The exceptions to this are those who took part in the first resurrection.

Inclination to sin: see Question 227. and explanation First resurrection: see Question 574.