You most likely believe it, but don't say it.
I don't know about any of these later people like Mateo Ricci, but traditionally Christians have
not believed that, LoAmmi. This isn't a bit of sophistry on my part, just a reminder to all involved that the first generation after the apostles who carried on their teachings such as St. Justin Martyr (AD 100-165) also carried on this idea. St. Justin Martyr, in fact, introduced the term "Spermatikos Logos" (lit. Seeds of the Word) to describe how it is that every belief system existing prior to Christianity has at some basic level these 'seeds of the Word', aspects of their teachings and practices that point to Christ and the unique truth of Christianity. Other ideas which developed later may say many different things, but they're at variance with this earlier teaching from St. Paul, St. Justin Martyr, St. Basil of Caesarea (who in the 4th century even wrote a treatise on the edifying use of pagan literature by Christians; many modern day Christians would no doubt be uncomfortable with this, but that's on them), and others. While it's not very popular in Western forms of Christianity, it bears repeating that in the East, or rather, what we might call the (ecclesiastical) 'Orient', among the native peoples there like the Copts, Syriacs, and Tewahedo Ethiopians and Eritreans, there is a great deal of emphasis placed on the continuity of their old belief systems and practices within their adopted religion of Christianity. For the Copts, they like to point out that their hymns use melodies that they say date back to the Pharaohs, and of course their language itself does too. Among the Syriacs, too, they are proud -- not at all ashamed -- to have such a long and glorious pre-Christian history, and names and imagery connected to their pre-Christian past is common, e.g., men with names like Ashur, Sargon, etc. are common. For the Tewahedo, their affinity to their pre-Christian, supposedly Jewish past goes so far as to include Saturday worship in addition to Sunday as the normative practice, a peculiarity that has been normative for centuries and they say reflects their original practice. They also forbid pork and have some other laws that are similar to Jewish dietary laws (though from what I understand, they do mix milk and meat).
It would be hard to keep these practices and other aspects of the faith and culture alive if they thought they were bad by virtue of not being Christian (originally).