The Catholic Church has been converting pagans for the last 2,000 years.
And incorporating their pagan beliefs and customs into Catholicism.
If the candles which were formerly distributed at the Saturnalia are now identified with the feast of the Purification of our Lady? What, I ask, is there so surprising if holy bishops have allowed certain customs firmly rooted among pagan peoples, and so tenaciously adhered to by them that even after their conversion to Christianity they could not be induced to surrender them, to be transferred to the worship of the true God?" (Baronius, "Annales", ad ann. 58, n. 77). (as cited in Thurston, Herbert. "Lights." The Catholic Encyclopedia. Vol. 9. Nihil Obstat.October 1, 1910. Remy Lafort, Censor. Imprimatur. +John M. Farley, Archbishop of New York. New York: Robert Appleton Company, 1910.21 Dec. 2009 )
Even though God said not to.
9 When thou art come into the land which the Lord thy God shall give thee, beware lest thou have a mind to imitate the abominations of those nations...12 For the Lord abhorreth all these things, and for these abominations he will destroy them at thy coming. (Deuteronomy 18:9,12, DOT)
Not when it allows syncretism, that they can incorporate their pagan beliefs into Catholicism.
Conversion is not regeneration. The Catholic Church does not and cannot save anybody. Regeneration, saving a person, giving a human new spiritual absolute life is a sovereign power that God arrogates exclusively to Himself.