Where do fundamentalists get the idea that Catholic Baptism involves sprinkling of water?

From their ignorance and arrogant belief they know everything!

Baptism is by immersion. The New Testament was originally written in the Greek language. The Greek word we get the word "baptism" from, means to immerse. The verses that speak of baptism literally are speaking of immersion or dipping someone into the water. Immersion is to dip down into the water. It is an overwhelming. The one being baptized is lowered into (until he is completely under) the water and then lifted up out of the water. It is not just sprinkling or pouring a little water on top of someone. This can also be seen in Scripture. John 3:23 says, "Now John also was baptizing in Aenon near Salim, because there was much water there. And they came and were baptized." Only immersion requires "much water". Baptism is described as going down into the water and coming up out of the water. (Matthew 3:16-17, Acts 8:38-39) Only immersion has the one being baptized going into the water. Also, baptism is described as a burial. (Romans 6:3-4, Colossians 2:12) Only immersion buries the one being baptized. It's funny that the only place that people have trouble understanding baptism is in religion. If someone were to say they were "baptized in debt", would you think they had just a sprinkling of debt (a few bills)? No, someone described in this way is figuratively "covered up" with debt. I saw a sports article that said the freshmen on a football team had an "early baptism". Of course it mean they were plunged into full sudden participation in the program. They did not just see a sprinkling of activity, but they were fully involved. If we can understand this everywhere else, why not in religion?

At any baptism I've been to, the water was poured.

I think the fundamentalists might equate pouring with sprinkling, at least, one of their websites that I saw did equate them. So maybe that's what they mean.

# 1239 of the Catholic Catechism says that the essential rite consists either of a triple immersion in the baptismal water, or "from ancient times it has also been able to be conferred by pouring the water three times over the candidate's head."

It actually doesn't mention sprinkling.

St. Thomas Aquinas says that what is essential to the sacrament is the washing with water, but the particular way the washing is carried out is not of the essence of it:

"What is accidental to a thing does not diversify its essence. Now bodily washing with water is essential to Baptism: wherefore Baptism is called a "laver," according to Ephesians 5:26: "Cleansing it by the laver of water in the word of life." But that the washing be done this or that way, is accidental to Baptism. And consequently such diversity does not destroy the oneness of Baptism. " (Summa, Part 3, question 66, article 9)

very few modern catholic churches have facilities for full immersion.

where there was a shortage of water, or not near a running stream or river, the early church allowed the sprinkling over the head of the recipient

Baptism is symbolic brain-washing.

Are you seriously arguing with people of your own faith on technique of applying water to forehead?

wow, just wow.

You're kidding, right?