Like the religious leaders of Jesus' day, most theologians tend to focus WAY too much on the physical, and on laws.
John 4:24 God is spirit, and his worshipers must worship in spirit and in truth."
It has been suggested by some that we should "Have nothing to do with pagans"... which is what the Pharisees told Jesus:
Matthew 9:10 While Jesus was having dinner at Matthew's house, many tax collectors and "sinners" came and ate with him and his disciples. 11 When the Pharisees saw this, they asked his disciples, "Why does your teacher eat with tax collectors and `sinners'?" 12 On hearing this, Jesus said, "It is not the healthy who need a doctor, but the sick. 13 But go and learn what this means: `I desire mercy, not sacrifice.' For I have not come to call the righteous, but sinners."
and again...
Matthew 12:2. When the Pharisees saw this, they said to him, "Look! Your disciples are doing what is unlawful on the Sabbath." 3 He answered, "Haven't you read what David did when he and his companions were hungry? 4 He entered the house of God, and he and his companions ate the consecrated bread--which was not lawful for them to do, but only for the priests. 5 Or haven't you read in the Law that on the Sabbath the priests in the temple desecrate the day and yet are innocent? 6 I tell you that one greater than the temple is here. 7 If you had known what these words mean, `I desire mercy, not sacrifice,' you would not have condemned the innocent. 8. For the Son of Man is Lord of the Sabbath."
Almost all teachings about "false doctrines" were directed towards those who wanted to take freedom away from the believer with rules, rules and more rules. Knowledge "puffs up", but the freedom that comes from having your heart changed so you don't NEED rules is amazing. We are simply to love people into the kingdom, becoming all things to all men as Paul put it. Don't let the legalists destroy your love or turn your freedom into another version of the "law".