only read the top few posts.
they knock on people's doors because of the same reason they go to the streets.
Mark 16:15,
And he said unto them, Go ye into all the world, and preach the gospel to every creature.
There's a reason why they do it and also reasons why Witnesses don't celebrate christmas:
Jesus commanded that we commemorate his death, not his birth.—Luke 22:19, 20.
and birthdays too, both mentions of birthdays in the bible, Matthew 14: 6-10 & In Genesis 40:20-22, mention murder and aren't very nice things to celebrate on birthdays. also back to Luke, Jesus wanted his death celebrated. Also birthdays put you above God, the same way wearing precious metals & jewels, and having something that you see as more precious than God in your hands is forbidden by Allah in islam.
They can't have tattoos, as said in leviticus: 19:28, Ye shall not make any cuttings in your flesh for the dead, nor print any marks upon you: I am the LORD.
Or blood transfusions: 6"The Old Testament law required people not to eat flesh with the blood in it; rather, they were required to pour the blood out. See Gen. 9:4; Lev. 3:17; 19:26; 17:10-15; Deut. 12:16,23-28; 15:23; 1 Sam. 14:31ff. Further, they were not to directly eat blood of any animal - Lev. 7:26,27; 17:10ff; Deut. 12:23.^
The point of Jesus was to eradicate these laws such as wearing two different types of cloth: Do not wear clothes of wool and linen woven together. (NIV, Deuteronomy 22:11)
cross dressing: A woman must not wear men's clothing, nor a man wear women's clothing, for the LORD your God detests anyone who does this. (NIV, Deuteronomy 22:5) this is one of the reasons Joan of Arc was prosecuted.
Circumcision: And on the eighth day the flesh of his foreskin shall be circumcised. (leviticus, 12:3 as well as many OTHER ones. in 1 Corinthians 7:19 it says it doesn't matter if you are or aren't, god still loves you)
also locking your menstruating girls up, not washing when menstruating, etc etc etc were all supposed to be eradicated with the birth of jesus. they weren't. There are reasons for living your life in the bible, every choice has an explanation.