Would you please explain Matthew 6:17? It says "But thou, when thou fastest, anoint thine head, and wash thy face" but many people say something like do not take this verse literally, anointing one's head is not really important, what really matters is his/her attitude towards God. But I think since the Bible teaches us to "anoint thine head" when fasting, we should just do exactly as God says. Am I correct? By the way, what is the standard biblical way to anoint the head when fasting? Can one just use any hair oil?
You completely missed the point of the passage.
"Moreover, when you fast, do not be like the hypocrites, with a sad countenance. For they disfigure their faces that they may appear to men to be fasting. Assuredly, I say to you, they have their reward. But you, when you fast, anoint your head and wash your face, so that you do not appear to men to be fasting, but to your Father who is in the secret place; and your Father who sees in secret will reward you openly" (Matthew 6:16-18).
In the verses surrounding it, Jesus told his audience that some people practiced their religion for show. They want other people to see how religious they are. Thus, when they fasted, as the Old Testament law required, they made a big show of how much they were suffering.
Instead, Jesus stated that when we worship, it is to please God, not to please ourselves or others. So if a person fasts, he should act as he normally does, washing his face, putting on cologne, and all the other things a person who is having a good day does. No one else should know he was fasting and then God would reward him for his service to Him.
The anointing was not something special. In those days perfumes tended to be oil based. Scents were added to oils and then when applied to the head for styling the hair it gave the person a pleasant smell.