At the heart of the civil war sits King Charles I. Charles Stuart was vain, arrogant, self-righteous, and often cruel. But he wasn't the cause of the troubles of the 1640s. Yet it's rather hard to see how it could have all happened without him. In an age of personal monarchy, the character of the monarch had powerful political consequences. In the 18th Century, politicians were able to control the madness of George III; in the 17th Century, no one could stop the obstinacy of Charles I.
Through a combination of naivety and arrogance, at every turn, every juncture in the chaos of the civil war, he made the wrong choice at the wrong time. While others compromised and haggled, Charles stood forlornly for what he believed in.
The thing about Charles is that he was never meant to be King. As the younger son of James VI/I, the introverted Charles was not destined for the throne. It was all lined up for his alpha-male brother, Henry. But when he tragically died, the stammering, shy, and desperately inadequate young prince was thrust forward. Never meant to be king, he then demanded to be more than king.
Charles's father, James VI/I, had combined a belief in the sanctity of monarchy with an understanding that politics was the art of the possible. Having been King in Scotland, James was used to cutting deals and politicking. Charles understood no such thing. He was a strangely pious man and genuinely believed the actions of monarchy reflected the divine will of God. Charles faithfully believed that he was God's vicar on earth. Monarchy was not part of a political constitution - it was a mode of governance in and of itself. And any objection to the will of the monarch was nothing short of rebellion. In the words of one contemporary, 'he was the most obstinate person in his self-will that ever was, and he was so bent upon being an absolute uncontrollable Soveraigne that he was resolved either to be such a king or none.'
His refusal to accept any other points of view led him in 1629 to dismiss Parliament when it started asking awkward questions about his religious and financial policies. The relative success of his period of 'Personal Rule' during the 1630s, with decent harvests, an heir to the throne and no wars, only increased Charles' conviction in his divine sanction to govern.