Richard wrote:

Certainly holidays such as Easter and Christmas can remind one today of God's provision for man in sending his Son and showing Christ to be authentic. This passage is written to the early believers and/or Jewish people who may use the observance of certain so called "holy days" as a means of justification and sustaining righteousness".

Dear Richard,
God Bless your beautiful heart and thank you for writing.  The same could be said about the early believers because all the rites, feasts, sacrifices and holy days showed the people the truth of the Coming One Who would die to take away the sin of the world.  If we take a closer look at the word used for Shadow we will gain a greater understanding of the Apostles warning.  This applies to an even greater magnitude today then for the early believers in that they had a better understanding of the meaning of the shadows then the modern traditional ones made by men (like Christmas and Easter) not God.  We hope the following teaching helps.

The Greek word so translated, skia occurs seven times in the New Testament.

Matt. 4:16
The region and shadow of death.

Mark 4:32
Lodge under the shadow of it.

Luke 1:79
In the shadow of death.

Acts 5:15
The shadow of Peter passing by.

Col. 2:17
Which are a shadow of things to come.

Heb. 8:5
Example and shadow of heavenly things.

Heb. 10:1
The law having a shadow of good things to come.

In this article we are concerned chiefly with Colossians 2:17:

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: which are a shadow of things to come; but the Body is of Christ (Col. 2:16,17).

While the epistle to the Hebrews does not teach the truth of the Mystery it does lead the believer on from the rudiments of the faith to the reality found only in Christ, and speaks of the observances imposed under the law, as shadows of heavenly things and of good things to come. If this is Gods will for Hebrews, who had been under the law, how much more must it be so for Gentile members of the body of Christ, who were never under the law. While Colossians 2:17 contrasts the shadow with the body, there is no explicit reference to the title the body here, as meaning the church of that name. Shadow and body here, are placed over against one another, as example, pattern, and very image, are placed over against shadow in Hebrews. The reason for the altered term may be discovered in the nature of the things compared. In Hebrews there is a fulfillment of what had been adumbrated in the law, but in Colossians, we have already been told, that the Mystery had been hid from ages and generations (Col. 1:26), and had formed no part of the typical teaching of Moses. It is a happy coincidence that body can be used both of the opposite of shadow and of the new constitution of the church. Dean Alford, a member of the Church of England wrote:

We may observe, that if the ordinance of the Sabbath had been, in any form, of lasting obligation on the Christian Church, it would have been quite impossible for the Apostle to have spoken thus. The fact of an obligatory rest of one day, whether the seventh or the first (our italics), would have been directly in the teeth of his assertion here.

Much has been written by zealous teachers, that would put the believer into bondage, and exalt mere self-denial into a positive grace. Colossians 2 warns against the mere neglecting of the body (Col. 2:23) While much emphasis is laid upon the observance of The Lords Day as a Sabbath, one seldom comes across a positive exposition of the words, The living God, Who giveth us richly all things to enjoy. We are complete in Him, let us not in any sense step down from our high calling. Of the Galatians, Paul wrote I am afraid of you, lest I have bestowed upon you labor in vain -- and that because they had turned again to weak and beggarly elements, and observed days, and months, and times, and years (Gal. 4:9-11). The only religion ever given by God was done away at the cross. We have something infinitely greater than religion, we have the substance as opposed to the shadow the body is of Christ.

All God's Blessings,
The Believers