This is an important topic and one which needs to be considered seriously by anyone who believes that Wicca is the path for them.. Once upon a time everyone knew what the core beliefs of Wicca were because everyone studied the same set of beliefs.But as Wicca has grown and expanded things have changed. Some things have been added which have enriched the path. But often things have been taken away which change the subsequent journey into something no longer recognizable as Wicca.
Worse yet it has come to the idea that Wicca is whatever we want it to be. Things are added or removed on a whim, sort of a buffet spirituality. As an example I once encountered a person who wanted to know whether or not they could omit the God and Goddess from their path and still be considered Wiccan. Well no, you can't.
Wicca is a specific religion with specific beliefs and practices which make it Wicca and not something else entirely. While I do feel that change keeps us as a vital and living faith, I also feel that if you change the core beliefs and practices too radically what you are doing may be a valid Pagan path, but it is no longer Wicca.
A number of years ago on another message board my husband and I and several other Wiccans both traditional coven types and solitaries engaged in a long conversation as to just what constituted the core beliefs which made Wicca a specific spiritual path. At the end of the discussion we came up with the following. And while I feel these pretty well sum up Wiccan beliefs, I allow as how others may put different priorities on each category. Also note that while these elements need to be present for the religion to be called Wicca, there is plenty of wiggle room in them to allow for individual practices as well.
1. Wicca is a mystery religion.
2. Wiccans believe that Divinity is made manifest in both masculine and feminine Forms.
3. Wiccans believe that the world was created and is maintained by the joining together of these two Forms in the Sacred Marriage.
4. Wiccans believe that Divinity is immanent within the world, and therefore all that is is in some part Divine.
5. The dates for Wiccan observances are determined by the changing phases of the moon, and the turning of the seasons.
6. Wiccans hold a religious observance at the time of the full moon.
7. Wiccans believe that magic is efficacious when worked in the proper forms and setting as part of a Wiccan religious practice.
8. Wiccans believe that each person is able to experience direct contact with the Divine without a need for an intermediary.
9 A re-enactment (in some form) of the Sacred Marriage is a necessary part of Wiccan ritual.
10. The ethics and behavior of Wiccans must be guided by the Wiccan Rede.
11. Wiccans believe that the world will return to them the same sorts of energies they send out into the world.
I think it is important to consider seriously what constitutes the core of Wicca. The present tendency for people to think it can be anything they want it to be puts it in danger of becoming a meaningless term. Wicca is a specific path. If what it is is not to your taste there are other equally valid paths to chose from. Or one can create a path that is unique to yourself. But to try to apply the Wiccan label to something which is not what Wicca is all about is foolish and misleading. Labels are important because we must use them in order to communicate clearly. So chose to label what you do correctly.