What I mean is that on a relative scale, in how they relate to God and people, some sins have a much more significant impact, or I might say, are more grievous. Notice gluttony didn't make it into the Ten Commandments.
This may be going too far astray from the topic, but while there are scriptures to show some sins are worse than others, there are contradicting ones such as James 2:10 that says anyone breaking any of the laws may aswell have broken all of them, or words to that effect. Also, the 10th commandment (in one of the versions) says not to cook a goat in it's mother's milk. Is that to be considered worse than gluttony or homosexuality? That's going off into another topic altogether though, but the point is we can't even be sure which sins are worse than others according to the Bible.
But at the same time, the simplest explanation is not necessarily the correct one in terms of completeness. Simplicity may be easier to work with, but we may miss details. If we're looking for the whole truth; if we're looking for the complete picture, don't we push beyond functional simplicity? Man strives to go beyond "because it works!"
I think whenever people have said that a god was behind something we couldn't explain, they thought it was the simplest choice. Saying Thor created thunder was simpler than looking into how it really occurs. Yet it isn't simpler at all, it is much more complex. Static electricity, different temperatures in the air and so on may seem complex, but they are still a whole lot simpler than explaining where this god came from. If thunder is beyond understanding, then adding a god only makes the problem even bigger, because a god has to be even more beyond understanding.
I agree that man strives to go beyond 'because it works' (similar to 'because God did it') and it may seem that trying to explain it with science is more complex. In a way it is, because it takes more understanding than just thinking a god was behind it. But at the same time, once the answer is found, it still ends up being a lot simpler than having to explain the god.
We can explain how things work without any deity, but can we ever hope to fully explain why?
It depends what we're talking about. With the things that we can't explain, saying 'I don't know' is the best response, because it is foolish to think we will know everything our descendants will come to know. School children today know more about the Universe than the greatest scientific minds of 500 years ago. I expect it will be the same 500 years from now.
With no proof of a god, that line of thought cannot be pursued beyond imagination. There is no data to work with, no evidence of any kind. Rather than opening up the possibilities, it closes them off sharply. For example today, only the scientists who aren't saying 'God did it' are the ones that are trying to find out what was before the Big Bang. Like the scientists of old who wouldn't settle for 'Thor did it' when trying to explain thunder, the only way for us to progress is to take this god character out of the equation altogether whenever a mystery comes along.