But time as we define it began at the Big Bang. "Always" is a finite quantity.
This looks like a good time to repost a response I've used before on physics threads that might help you to understand:
The question, "what happened before Archduke Ferdinand was shot" is a well-formed question, as is, "what is south of Topeka, Kansas." The question, "what happened before the big bang" is an ill-formed question, as is, "what lies south of the south pole."
Imagine you are travelling south, down to the south pole. As you get closer to the pole, the east-west direction does a curious thing: it curls back upon itself in an ever-tightening circle, disappearing completely as you reach the point of the pole itself. At that place, the ground is as smoothly two-dimensional as anywhere else on Earth, but every possible direction points north, even directions that lie at right angles to each other.
Imagine that you can go backwards in time, back to the big bang. As you get closer to the big bang, space does a curious thing: the spatial dimensions curl back upon themselves in an ever-tightening circle, disappearing completely as you reach the singularity itself. At that event, spacetime is as smoothly four-dimensional as at any other event in history, but every possible direction points towards the future, even directions that lie at right angles to each other.
I stress that what I have laid before you is not an analogy, but two separate examples of the same phenomenon.
There may exist events that are external to the space and time dimensions of our universe, but none of them can be said to come before or after any events of our universe; they cannot be included in any causal framework such as history. Time itself is strictly internal to our universe. If we want to use words like "cause" and "before", we must needs keep our game pieces on the board.
Moreover, the energy that existed at the instant of the Big Bang was arbitrarily close to zero in quantity. You needn't be philosophically troubled by all the stuff you see in the universe, as it provably cancels to a large number of decimal places.
Some of your compatriots obviously believe in the beginning was "nothing" and cause isn't even neccessary.
Cause isn't necessary in any case. There are demonstrably uncaused events in the universe as it exists today. But the real point is that philosophically, the very idea of causality is subordinate to the notions of space and time, which are physical things that themselves are subordinate to the Big Bang. Demanding that the Big Bang have a cause puts the cart way before the horse.