Perhaps a clean inner force cannot be corrupted by and unclean outside force except through deception, (concerning mankind). And perhaps a large portion of the war for understanding concerns the age old battle between "the flesh" and "the Spirit" understanding.
Jesus taught ALL in parables if we are to take the gospel accounts for their word.
He freely mixed and celebrated with the destitute, the homeless, the poor and the "cast-offs" of his day (refugees?). In other words, he ate and drank with "the unclean" of Jewish society. That's where Jesus saw God.
In his Parable of the Leaven, he turned the default world of convention upside down. A story of a woman (scandalous!) hiding a bit of yeast (leaven) in an oven full of dough is compared to the Kingdom of God.
But we need to look at context to understand the impact of Jesus's teachings. This is something traditional Christian churches never do...
"You are to observe the feast of unleavened bread, since on this very day you brought your people out of Egypt..."
"For seven days no leaven is to be found in your houses; for if anyone eats that which is leavened, that person will be expelled from the congregation of Israel."
Yeast or leaven was also prohibited in connection with sacrifices and meal offerings.
In Paul's letters to the Corinthian community he associates leaven with malice and evil and the unleavened with sincerity and truth.
Paul does that because he was steeped in the tradition that understood yeast or leaven to refer to corruption.
Jesus's Parable of the Good Samaritan, the Parable of the Mustard Seed, the Parable of the Prodigal Son demonstrate this same dichotomy of clean/unclean.
In other words, God is found in the unclean and the corrupt.