I’m sure you could google him to find a lengthy introduction somewhere.
His historical significance lies in his rebellious and unorthodox treatment of Christianity. That is what he is most know for academically. Like Spinoza and Voltaire, his beliefs got him into a lot of trouble and he remains an enigmatic character in history.
However there is much “philosophy” in his writing, if not the thick technical ideas proposed by popular metaphysicians of his day, which handles most accurately the real existential conditions of the ethical life. Once he said of Hegel “he constructs great castles of ivory yet lives in the woodshed beside them,” expressing the unpractical application of the technical, metaphysical systems to every day life.
You might consider him to be an anti-philosopher, but remember that the historical setting which he was in created the atmosphere for his polemical attack on everything academic. With this he customized his style of writing to deliver extremely philosophical points, but in a unique and somewhat unphilosophical way. There has never been a philosopher even remotely comparable to Kierkegaard.
As a young boy, his father ordered him to place second in a test given to those children in his class. Now, you see that it would be much easier to place first or last, but to do just enough to be better than the third, but worse than the first, requires greate precision, intellect, and an understanding of the other children’s capacities. The young Soren had no idea that he would soon become a master at “sizing-up” the human being.
Kierkegaards strength is in his use of the subliminal device. Irony, parody, sarcasm, contradiction, paradox, dilemma, quagmire, all forms of “indirect” communication (inspired by the Socratic method) through which Kierkegaard stripped naked his reader and pulled the rug out from under him. He is the most ‘personal’ philosopher I have ever read. It is as if he is there winking at you when you discover the hidden meaning in his brilliant puzzles, and you say, with goose-bumps rising on your neck, “Aha!”
I have come to the decision that the three greatest philosopher of all time are Kierkegaard, Nietzsche and Sartre. With K and N, I see two sides of a single coin…with S I see the currency of it put into action and spent.
An excellent book to get is “Kierkegaards Parables.”