Where do the modern day Christians get their beliefs about heaven?

The Jews certainly don't believe in heaven as modern day Christians know it:

See here

Or Here for scriptural references

Or Here for more

So, where does the idea of immediate salvation after death come from? Let alone the harps, wings, and other assorted silliness?
You would think that since the Christians inherited the Jewish God that the beliefs should be synonymous. Yet they completely aren't...

Lets see what my bible scholar readers have to say on that.