What “pollution from idols” means

It does not mean the golden calf had an "accident."

Nor does it mean instances of really bad singing on "American Idol."

At the time of today's first reading (Acts 15:7-21), "pollution from idols" would have meant association with objects of pagan worship.

How to avoid this? For one thing, don't worship in pagan temples or build little pagan shrines in your house.

But there was also a much more subtle issue in play at the time.

Often, after animals were sacrificed to idols, the meat would be sold on the open market. Since ancient Rome lacked today's truth-in-labeling laws, Christians might then unknowingly buy and consume meat that had been sacrificed to a pagan idol (although the meat would be hormone and antibiotic free [that's a joke, son]).

St. Paul addresses this concern about idols in 1 Corinthians 8.

As to the eating of food offered to idols, we know that 'an idol has no real existence,' and that 'there is no God but one.'.... However, not all possess this knowledge. But some, through being hitherto accustomed to idols, eat food as really offered to an idol; and their conscience, being weak, is defiled. .... And so by your knowledge this weak man is destroyed, the brother for whom Christ died.
(1 Corinthians 8:4,7,11)

Pagan idolatry seems to be on the rebound nowadays, especially as inadequately evangelized and catechized people try to "find themselves" in exotic or reinvented non-Christian spiritualities tied to statues and other objects.

The Scriptural warnings against explicit idolatry thus seem quite relevant today.

One must also be on guard against the implicit idolatries that pervade our modern life and culture: materialism, hedonism, intellectualism, and egotism.

Material things, pleasure, intellect, and self-concern all have their place, but they have become the center of existence for too many in the world today.

We as Christians, of course, know that the only God, the only ultimately satisfying reality, is God and so we worship God instead of the idols of this age. Yet even we are not immune to the "pollution" from these idols.

Moreover, we need to be attentive to the same concern Paul expresses to the Corinthians.

Even though we in our hearts may not be idolaters of money, pleasure, etc., perhaps we should give a thought to how others might be led astray by the particular way we are involved in these things.

Take care lest this liberty of yours somehow become a stumbling block to the weak.
(1 Corinthians 8:9)

Little children,
keep yourselves from idols.
(1 John 5:21)