Some amalgamation of pagan myths and superstitions with with the things of the Gospel is certainly true. They are not things found in the document of the New Testament. They are the leaven added in traditions that corrupted the fine flour of the pure teaching of the New Testament.
This was predicted by Christ in a couple of parables. One is the parable of the woman who HID leaven in three measures of meal until the whole lump was leavened.
Another parable He spoke to them. The kingdom of the heavens is like leaven, which a woman took and hid in three measures of meal until the whole was leavened. (Matt. 13:33)
And another like it - the parable of the mustard seed that grew out of proportion into a huge tree with demonic things roosting in its branches.
Another parable He set before them, saying, The kingdom of the heavens is like a grain of mustard seed, which a man took and sowed in his field.
Which is indeed smaller than all the seeds, but when it is grown, it is greater than the herbs and becomes a tree, so that the brids of heaven come and roost in its branches. (Matt. 13:31,32)
Both these parable should be understood negatively as the corruption and bloating of the Christian church into a huge world wide mixture of superstition, hypocrisy, and corruption.
This is the abnormal degradation of the church He founded into a huge evil organization of truth MIXED with error, deceit, superstition, and hypocrisy.