@pe7erpark3r I am a Catholic, and I do not know of a rational reason not to believe in angels. According to my understanding of the holy book, they exist and they are here to guide us on our path towards God.
For it is written: “ ‘He will command his angels concerning you to guard you carefully; - Luke 4:10
Anyone who claims to be a Christian and yet doesn't believe in the existence of angels must be either confused or an iconoclast.