Of course we don't worship Nimrod.
You must have read "The Two Babylons" by Rev. Alexander Hislop.
Hislop is not a reliable historian, and citing pagan parallels is insufficient evidence for any pagan influence claims.
If you read that Encyclopedia Americana, Encyclopedia Britannica, Encyclopedia Judaica, Encyclopedia of Religion, New Catholic Encyclopedia, and World Book Encyclopedia you'll find that not one says anything about Nimrod and Semiramis being husband and wife. They evidently did not live in the same century.
Following Hislop’s teaching, some claim that round objects (such as round communion wafers) are symbols of the Sun-god. But they fail to mention that the manna given by God was round (Ex. 16:14, KJV). Some are ready to condemn all pillars and historical monuments as pagan. But they fail to take into account that the Lord appeared as a pillar of fire and that in front of his temple there were two large pillars (Ex. 13:21–22; 2 Chr. 3:17).
In Eastern cultures, the many-seeded pomegranate was regarded as a fertility symbol. Nevertheless, 400 pomegranates adorned the two pillars in front of the temple (2 Chr. 4:13). Pomegranates alternated with bells on the robe of the high priest (Ex. 39:24). The Israelites did not refrain from using the pomegranate symbol, even though pagans in nearby Syria worshiped a god named Rimmon, meaning "Pomegranate" (2 Kgs. 5:18; Strong’s Concordance, 7417, 7416).
The harlot called "Mystery Babylon" is described as being "arrayed in purple and scarlet" (Rev. 17:4). Some immediately link these colors with the bright and highly decorated vestments worn by the pope and others within the hierarchy of the Catholic Church. But these colors do not establish that connection.
Purple and scarlet were used for the tabernacle curtains (Ex. 26:1), the veil of the temple (2 Chr. 3:14), and garments worn by the Old Testament priests (Ex. 28:6, 8, 15). An early Christian convert, Lydia, was a seller of purple goods (Acts 16:14). Proverbs mentions that the family of the "good wife" is clothed in purple (Prov. 31:22). Daniel—certainly not a compromiser with worldly ways—was honored by being clothed in purple (Dan. 5:29).
"Mystery Babylon" is described as being seated on "seven mountains" (Rev. 17:9). The claim that this chapter is about the Catholic Church does not fit the overall text, but because Rome is known as "the seven-hilled city," some suppose that this is the intended meaning. Hislop, for example, described the pope as "he who has his seat on the seven hills of Rome."
The seven hills are Palatine, Capitoline, Quirinal, Aventine, Caelian, Esquiline, and Viminal. The pope’s seat is on the Vatican hill, across the Tiber to the west, not one of the seven. A seven-hilled city would more likely describe pagan Rome, not papal Rome.
Moreover, if the word mountains is taken literally, the hills of Rome would hardly qualify. The highest is Quirinal at 226 feet above sea level. St. Peter’s Basilica—just the building—is nearly twice as high. I speak from first-hand experience, having climbed the stairway of the dome all the way up in 1978. It is 434 feet from the floor to the cross on top.
Taking a stand against "paganism" should not be carried to a foolish extreme. We do not refrain from using the word janitor, even though it comes from Janus, the Roman god of doors and gates. We do not avoid using the word cereal, even though it comes from Ceres, the goddess of grains. We do not refrain from using the word panic, even though it comes from the god Pan, who went about scaring people. We don’t refuse to visit a museum, even though the word comes from the Muses, the nine daughters of Zeus who presided over learning and arts.
http://www.catholic.com/thisrock/2005/0505fea4.asp