We ought to detest these heathen meetings and assemblies, if on no other account than that there God's name is blasphemed— that there the cry “To the lions!” is daily raised against us — that from thence persecuting decrees are wont to emanate, and temptations are sent forth. What will you do if you are caught in that heaving tide of impious judgments? Not that there any harm is likely to come to you from men: nobody knows that you are a Christian; but think how it fares with you in heaven.
For at the very time the devil is working havoc in the church, do you doubt that the angels are looking down from above, and marking every man, who speaks and who listens to the blaspheming word, who lends his tongue and who lends his ears to the service of Satan against God? Shall you not then shun those tiers where the enemies of Christ assemble, that seat of all that is pestilential, and the very super incumbent atmosphere all impure with wicked cries? Grant that you have there things that are pleasant, things both agreeable and innocent in themselves; even some things that are excellent.
Nobody dilutes poison with gall and hellebore: the accursed thing is put into condiments well seasoned and of sweetest taste. So, too, the devil puts into the deadly draught which he prepares, things of God most pleasant and most acceptable. Everything there, then, that is either brave, noble, loud-sounding, melodious, or exquisite in taste, hold it but as the honey drop of a poisoned cake; nor make so much of your taste for its pleasures, as of the danger you run from its attractions.
Source: De Spectaculis (The Shows) (New Advent)