On the contrary, Satan has no right to any symbols, and to the extent we can deprive him of those which his followers have managed to associate with him, each case of that is a victory for the Church, in which we will be aided in our struggle by God and His angels, so that the fallen angels, the demons, may continue to be denied. For every time we deny Satan, the evil one, our adversary, it is a victory for us made possible through the infinite grace of God, for which we should not be proud but filled with thanksgiving for His loving-kindness.
Thus, at present, it is of particular importance for Christians to object vehemently to the abuse of the Cross of St. Peter, who, out of respect for our Lord, was crucified upside down. Yet some vile occultists use an inverted cross as a Satanic symbol. This is a recent development and it is one that Christians should oppose vigorously.
I think you have it completely backwards. Pagan symbols have not infilitrated the Church, but rather, the Church has infiltrated Pagan symbols!
Why limit ourselves to those which predate the passion and resurrection of our Lord, God and Savior? Most of the ancient Pagan religions died off, which is good, but new false religions appeared in the centuries before and after the birth of our Lord in Bethelehem, such as Buddhism, modern forms of Hinduism, Jainism, Neo-Platonism, Mandaeism, Yazidism, Manichaenism, Montanism, Arianism, Islam, Sikhism, Unitarianism, Unitarian Universalism, Mormonism, the Jehovah’s Witnesses, Christian Science, Scientology, the Hare Krishnas, the Osho/Bhagwan/Neo-Sannyasin cult, Falun Gong, the Bahai faith, Cal Daism, Santa Muerte, Santo Daime, John Frum and other cargo cults in the South Pacific, Neo-Paganism, Wicca, et cetera, to a nauseating extent. And new ones pop up constantly. Most recently, we had the revelation of that disgusting NXIVM cult, which appears in a vile manner to have worshipped sex, money and its perverted founder, and which managed to secure an appearance by the Dalai Lama, who many Christians forget is the leader of an anti-Christian religion, whose government used to inflict brutal punishments on the Tibetan people, such as gouging peoples’ eyes out, even during the lifetime of the current Dalai Lama. Of course, the PRC is no better; Communism is also a false religion that in terms of its propensity for violence against Christians is rivaled only by Islam.