The Victorians ran out or grave sites in London, and started burrying people on top of those already dead.
It lead to all manner of public health problems, and so they designated HUGE out of town cemetaries - designed to be big enough for "all time", like Highgate Cem'y (final resting place of Karl Marx I seem to recall).
Guess what - they're full, and after only ~150 years.
As far as I'm aware, there is no clear statement in scripture that you MUST have your body to get salvation, although there are some passages that rest on interpretation.
I think we should revere the graves of the fallen in war and so on, as they are markers for their sacrifice. I revere the symbols of their life, not the evidence of their death.
I have no faith in any supernatural entities (God, the Devil, Cookie Monster, etc) but I have respect for those that do, and out of that respect I try to honour the rites that are expected - such as not walking on graves, taking my hat off in Church, putting my hat on in Synagogue, taking my shoes off in a Mosque and so on.
Oddly enough, the last vestige of my Church school upbringing causes me to light candles "in memoriam" whenever I visit a Church that has the facility - but I do that to help me focus on their memory, not to carry my prayers to heaven...
The dead are dead. Treat their remains with respect, but move them to a place where nobody needs the land for a railway line.
When I'm dead you can bury me at sea - it'll show my ex-wife that I mean business - she threatened to dance on my grave.
