Colossians 2:16 is not extrabiblical for the simple fact that it is in the Bible. How it supports Sunday worship beats me because it refers to ceremonial sabbaths that were part of the law of Moses.
Where does the word "ceremonial" come in on that verse? How did you decide that the Saturday Sabbath was in fact NOT a Sabbath in a verse speaking generally of Sabbaths? Where does Paul exclude ANY Sabbath from his teaching there? Is it Paul excluding it or is it you?
Ka-Bella, if you read Colossians 2 from the beginning it will be clear what kind of sabbaths Paul is referring to. He even mentions circumcision and that some people will try to deceive believers with vain philosophies.
8 Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.
9 For in him dwelleth all the fulness of the Godhead bodily.
10 And ye are complete in him, which is the head of all principality and power:
11 In whom also ye are
circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
12 Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;
15 And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.
16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of
the sabbath days:
17 Which are
a shadow of things to come; but the body is of Christ.
18 Let no man beguile you of your reward...