Why are the gravediggers debating about whether Ophelia
deserves a Christian burial?

They are debating this as her cause of death was s uicide.

Explanation:

One argument is that the Church forbade burials when a deliberate death happened on consecrated ground, as Ophelia's did. The argument against this is that Ophelia's death was not in fact a s uicide but accident, or if it was s uicide it was simply a product of her madness and not a reflection on Ophelia's true Christian soul.

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.

might need to ask questions people no or have read somthing about.