Hi. The other day I was looking at a Catholic dating website and got aroused. I was wondering if this is a mortal sin. Even though all the women were dressed modestly and I did not at anytime entertain any impure thoughts. Yet I was still aroused. Please tell me if its a mortal sin as I attend mass everyday and I wish to receive holy communion tomorrow. I tried pinching myself several times to stop the arousal. Oh and as a final note I have struggled with impurity in the past and have made it a month so far without any relapse. I'd really like to know if I've committed a mortal sin as I don't want to do it again.
Involuntary arousal is never a sin. Even voluntary arousal is not a sin for married people.
For a sin to be mortal, the act must be objectively sinful, the person must know that it is sinful and he must freely choose to sin.
Fr. Vincent Serpa, O.P.