I’m Catholic and sure do believe in Satan / The Devil. I don’t know any Catholic that doesn’t believe in the Devil / Satan.
CATECHISM OF THE CATHOLIC CHURCH SECOND EDITION 2851 In this petition, evil is not an abstraction, but refers to a person, Satan, the Evil One, the angel who opposes God. The devil ...
V. Do you reject Satan?
R. I do.
V. And all his works?
R. I do.
V. And all his empty promises?
R. I do.
V. Do you believe in God, the Father Almighty, creator of heaven and earth?
R. I do.
V. Do you believe in Jesus Christ, his only Son, our Lord, who was born of the Virgin Mary was crucified, died, and was buried, rose from the dead, and is now seated at the right hand of the Father?
R. I do