In Edwards' view, what must sinners do to save themselves?

This sermon,
and others like it, was designed to be a wake up call intended to make people take religion more
seriously. Full membership in the puritan church required a conversion
experience. However, over subsequent generations, descendants did not have the
same conversion experiences and were seemed (to the church authorities) to be living less
spiritual lives. So, the church started the "Half-Way Covenant" where children of
those who had conversion experiences could be partial members of the church. The hope was that
partial members would eventually be persuaded to become full members via having a true religious
conversion experiences. In a sense, this meant something similar to being "born
again," a term that we use today. 

However, preachers like Edwards
thought this was too lenient and accommodating. Therefore, he tried to scare people into having
a genuine conversion experience as soon as possible. For Edwards, this is the only way for a
person to be saved.

He claims that men/women will slip and God will not save
them. In other words, he is saying that they will slip unless they convert.
"Their foot shall slide in due time." Without a conversion, the person will
fall: 

Unconverted men walk over the pit of hell on a
rotten covering, and there are innumerable places in this covering so weak that they will not
bear their weight, and these places are not seen. 

Edwards repeats the danger of being unconverted. "The use of this awful subject
may be for awakening unconverted persons in this congregation." Again, the sermon is meant
to be a wake up call. This is why it is so laden with fear tactics and threatening
language.