It depends: 1. If 你 are asking about being faithful to your spouse - ie not cheating on him/her then it is very important. 2. It is very important to be faithful to your God. I am a Christian and I feel it is important not to be mislead into worshiping false gods. We see it so prominent in the world today, where worshiping a false god is disguised in "exercise". 3. To be faithful to 老友记 或者 spouse - as in support their activities, etc. That would depend on whether these people are being good. I do not feel that if someone is doing something legally 或者 morally wrong that we should be faithful to them. We must follow our own judgement - even if it means loosing a friend.
Its very important because being faithful makes your relatioship last longer and it gives 你 peace of mind 你 dont have to worry about being caught 或者 making up lies to cover up 或者 even being paranoid
That depends. Like, I give zero fucks about god,but I tend to be reasonably faithful to people most of the time. But like, they have to exist for me to have faith in them, so that rules God out.