I was hoping someone could clarify something for me. I have noticed in a lot of spells and rituals, you are supposed to invoke either THE goddess and THE god, or you own goddess and god. Must you choose one? And do you just choose one god and one goddess that you connect with? Can they be from different mythologies? What do you invoke them for? I'm confused and it would be great if you could help me out.
No, you do not have to choose a god or goddess. There are plenty of atheists and non-religious folk who practice different aspects of magic, spell casting, and even witchcraft.
Yes, you can choose a god or goddess to connect and work with; however, there are many people on here who also believe that a deity chooses you. Some people do choose their deities based on those who seem to have similar personalities and what that deity may represent. Choosing a god and goddess may very well just be for a given situation or magical working but not necessarily on a level where you work with them daily and have a personal relationship with.
To me, I do think that the deities whom you work with and incorporate in your practices can be from different religions as long as you do not destroy the religious canon (the structure of the religion) of those deities from different myths and religions. It is also might be good to learn the difference from UPG and PCPG as well.
Invoking is simply to call upon a deity rather it be through prayer or whatever. People invoke deities to help them in their workings as a means to help carry out the working, for protection, and that kind of thing.
Here are some resources that may help assist you further:
UPG and PCPG in Practice by Personified - http://www.spellsofmagic.com/read_post.html?post=598601
Choosing a Goddess & a God by Flora Sage (charmingpixieflora) - https://www.youtube.com/watch?v=4VhpJ3imua4
Finding Your God and Goddess Deity by The Chira Project -https://www.youtube.com/watch?v=l9xDGGjV-BU
First off, you most likely mean evoking which is calling upon a deity or like petitioning Them. Invoking is calling upon a deity into one's self. It all kinda depends on your personal beliefs as long as you aren't appropriating closed cultures and religions. Some people are soft polytheist which basically means all gods are different aspects of one universal source or something similar. Maybe you're a hard polytheist which means each god and goddess are separate entities. You don't really need to choose a deity, plus they might not really honestly really like you back.
TheLover, invoking is correct by definition but it may be incorrect from a religious standpoint. It seems that is more from a personal thing. As different people classify it differently. Oxford Dictionaries and Merriam Webster says what I have used it in context of.