The idea of God always existing

[Undeceived]

If there wasn't time or space, then time and space began at the Big Bang.

Why? Time, maybe, but why space? Space could very well be eternal.

Possibly, depending on what you call 'space'. If it has no qualities and no bounds, it is nothing, and there might be no point in arguing beginning at all. You could call such a state eternal. But that's no victory for the generation of matter, because if a vacuum has the mere potentiality for material, that material only becomes an actuality with a third-party cause (Aristotle). By that same line of logic, any kind of plane for quantum fluctuations also needs a cause.

The idea of space being arranged into an omnipotent being prior to the beginning of the universe without a cause, allowing said sentient and omniscent being to cause the universe, on the other hand, does not seems valid at all.

No one was proposing space arranging into a being "prior to the beginning of the universe." They were, however, explaining that the first cause in the chain must have no beginning--it must be pure actuality. This could be a divine being, or an undiscovered force (no evidence). Or there could be a way for our current natural laws to be violated, eliminating the need for a cause->effect (with all evidence to the contrary). Again I ask, which is the most plausible to you? Or do you have another proposition to add to the list?

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Wrong. "Beginning", without a spatio-temporal context, does not make any sense.

Time starts the instant time itself comes into existence. In the timeline of time, time is at point 0. There is no "before" but we can look back and say there was a start. If you see this differently, please explain.