You can find previous chapters here, here and here.
Kierkegaard opens this chapter with the idea that if it were not for the duty of love there would be no concept of "neighbour". Christ, has taken preferential love (which is not Christian) off the throne and replaced it with the unconditional and eternal love of "you shall" (which is Christian love).
Many Christians, however have gone back to putting erotic love and friendship unduly back on the throne, which, for Kierkegaard, simply will not do. These loves are loves of passion, they live based on either/or - either they exist (and nothing else) or they do not. It would be confusing if Christianity were to teach that both, these passions and Christian love, could live in harmony, because they simply can not.
Kierkegaard goes on to argue that we should not be deceived into thinking that Christendom, in its old age, has matured. In comparison to it, Those with in it are yet babies. Christians have not been enlightened to true love, but deceived. Kierkegaard returns to the poetic vision of love that many have mistaken for Christian love. It is not bad to consider the poets and artists, but the listener or reader has neglected to think deeply (indeed, Christianly) about them, therefore they have been brought down into their way of thinking. We need to scrutinize the poet and ourselves in order to help others become deeper and deeper Christians. Christendom then is not a destination, but a signpost. We have not arrived, and Kierkegaard wonders how we ever will if the road is only followed one day a week.
Christian love is then is love of neighbour - the love of all - while erotic love and friendship is preferential - it's the love of one. It is impossible to love in both ways simultaneously. The poetic love is never an obligation, and there in lies the problem. This Christian obligation to love, is to love everyone.
"Christianity never suffers a man to go in vain, not even a single step, for when you open the door which you shut in order to pray to God, the first person you meet as you go out is your neighbour whom you shall love. Wonderful!"
What's wrong with passionate love? It's arbitrariness makes it merely self-love. Kierkegaard refers to the friend or lover as the "other-I" as friends and lovers expect reciprocation, in choosing who to love, one only loves oneself. Christianity has a higher demand, self-renouncing love. "Love your neighbour as you love your beloved", but expect nothing in return.
The neighbour is your equal. If you love him and think him higher, you are not loving a neighbour. Same, if you think him lower, your are not loving as a neighbour. If you think him well educated, dumb, rich, poor - you do not love as a neighbour.
"One's neighbour is one's equal …. Loving one's neighbour means equality."