Fundamentally, Paganism is disjunct from Christianity. A person can only be one or the other. While technically a Pagan is not forbidden to worship Jesus Christ (but shouldn't or wouldn't, see below), Christians are condemned to eternal punishment if they worship anyone other than the persons of the Trinity. If you are Christian, worshiping other Gods is one of the most massive sins you can commit. (See Ex. 22:20—"He that sacrificeth unto any god, save unto the LORD only, he shall be utterly destroyed"; also 1 Jn. 5:21; 1 Cor. 10:20; Dt. 32:17; Ex. 32:1-6; 1 Kgs. 12:28-30.) Here is a link to a fairly normative, if biblically founded Evangelical presentation of the Christian understanding of other Gods. If, as a Christian, you think you can dodge this problem, you will have to answer to your God. He forbids the worship of other Gods, as well as magic, divination, astrology, and so forth, under pain of damnation. These scriptures dispose of the Christian side of the equation: You can't be a Christian and do Pagan things.

If you are Pagan, worshiping Jesus Christ, or His Father or the Holy Ghost, is a different kind of problem. There is nothing to forbid such, but why would you?

Technically worship strengthens that which is worshiped (see my blog) both in the world and in the life of the worshiper. Thus worshiping any or all of the Trinity makes you more Christian and less Pagan. This looks good to Christians. Christianity and its God desire our (that is, Pagans and everybody else) elimination through ideological imperialism and ethnocide; all must be converted. If you want a good solid Christian vision of this, read the Revelation of John. Jesus promises to throw us all in the Lake of Fire, in other words to destroy us or torment us for all eternity if we do not bend the knee and confess that he is our Lord and Savior.

Therefore for a Pagan to worship this Deity, Yahweh and Co., in all sincerity and fullness is rendering aid and comfort to an enemy: a Being who wishes Pagans destroyed or to have their religions and culture removed by conversion.

There are some qualifications to this statement: Rendering due honors in His hall is just being polite; He is a God after all. Attending the worship service of a neighbor, friend, associate, or family member in support of them is to be distinguished as well. That's just being respectful and caring. There are probably other times when doing something technically worshipful but which places persons over ideology and which are caring or honorable is appropriate. I can't be exhaustive. This requires good judgment.

The main problem is that Yahweh & Co., and Their followers, have declared themselves our enemies. We don't need to be out to destroy them to be enemies, because they already seek our destruction; that's what makes them our enemies. Worshiping any of the Three of Them is supporting the Deity that seeks to eliminate all of us "idolators" and "demon" worshipers. Ever been witnessed to? Have you seen the theocratic and Dominionist movements within Christianity? These are not aberrations attributable to a few bad apples, but central to the system of Christianity.