Q. 896. Has the Holy Eucharist any other effect? A. The Holy Eucharist remits venial sins by disposing us to perform acts of love and contrition. It preserves us from mortal sin by exciting us to greater fervor and strengthening us against temptation.
Unfortunately, I believe Havoc is misrepresenting the Holy Eucharist. The above does not say that partaking of the Eucharist provides a "get out of sin card". I believe it means, based on Scripture, that partaking of the Eucharist is something one can do to help strengthen the soul against temptation. It's not the only thing one can do - I reject those who receive the Euchraist and do nothing more - and there is indeed more to do.