Thou Shall Spread the Good Word, or Not?

One of the most interesting things that I have seen in religious practices is the varying ideas of social or community responsibility. What I mean by is this is the 'duty' for lack of a better word, that is given to members of a certain faith to 'spread the word', or 'bring followers to the light' of whatever truth that is supposed to be uncovered. In Christianity we are told that while the process of getting to heaven is your responsibilty, if you do not share the teachings of Christ with others, you are not sharing the salvation of The Lord and that is a great sin. In Islam there is also responsibility of the man of the family to make sure the rest of the family is following correct Islamic practices. This weeks readings concerning the Buddhist faith stance on this has confused me however.

In The Concealed Art of the Soul by Ganeri, one of the most famous stories is told about the smilie of the raft. Now, this parable was told by the Buddha as a lesson of truth, but also of responsibility. 

"The Buddha tells the story of a man who, having built a raft in
order to get across from a dangerous place to a place of safety, then thinks
to himself 'This raft has been very helpful to me. Suppose I were to hoist
it on my head or load it on my shoulder, and then go wherever I want.'
The Dhamma is similar to the raft, says the Buddha: it is for the purpose of
crossing over, not for the purpose of holding on to."

(Ganeri, 45-46)

In class we discussed the fact that it was not uncommon for people to be concerned with the self and nothing else. This fine line between what is considered selfish and self-consumed is toyed with in this reading as the man had to be selfish to cross over, but must not be self-consumed enough to not aid another in there journey. This becomes an area of difficulty for me, though as I am not sure if this is aid is given because of the feeling of responsibility or fear of bad karma, inhibiting the continuation of the man to parinirvana. 

After looking at other passages for guidance I also came across this quote in Mahayana Buddhism:

The Doctrinal Foundations by Paul Williams:

‘The Lord has admonished us and praised us that we should live in seclusion’. But it is the
hermit, who considers the monk who visits villages and mixes with laity to be possessed 
of impure morality, who falls to hell after death, while the altruistic preacher is revealed to
be the Buddha in a previous life (Braarvig 2000: 130–1; cf. also Karashima 2001: 159–60)

(Williams, 38)

After reading this, I felt as if I was even more unsure of the answer to this question. The problem for me lies in the fact that the quote leans so much towards the social responsibility ideas that it doesn't actually sound like Buddhism to me. Now I am very aware of my minimal knowledge of Buddhism and when I look back at the last sentence I am confused as to what I menat by 'sounding Buddhist' but it just seems very liberal in comparison to the conservative readings that we have done previously. 

What are these readings saying? Is there a responsibilty to spread the word? And if not then how has the teachings of Buddhism spread over the thousands of years? If there is a responsibility then why is the culture areound the process of enlightenment a singular one? How can one truly release the idea of 'self' if the self is apart of the whole that you are carry responsibility for getting 'to the other side?' Is there even a black and white answer to these questions?