It's Hard to Be a Saint in the City

Why does Catholic British MP Chris Coghlan believe he should receive the Eucharist while in a state of Grave Sin?

The House of Commons in the United Kingdom recently legalized the heinous act of assisted suicide. At least one Catholic member of Parliament is in the crosshairs because of it:

A Liberal Democrat MP was denounced by his Roman Catholic priest before his congregation and banned from communion after voting in favour of the assisted dying bill.

Chris Coghlan, the MP for Dorking and Horley, described his treatment as “outrageous”. He has complained to Richard Moth, the Bishop of Arundel and Brighton.

In the days before the vote, Coghlan was contacted by his local priest, Father Ian Vane, who suggested a vote in favour would be “obstinately persevering” in sin and that Coghlan would be refused communion if he did so.

Vane, the priest at Coghlan’s local church, St Joseph’s Catholic church in Dorking, Surrey, wrote: “As priests, we are custodians of the sacraments.”

Issues like this are always complicated, usually because non-Catholics like to interject their feelings in the matter even though 1) they aren't Catholic, 2) don't understand Catholic teaching, and most importantly, 3) don't believe that the Eucharist is the true presence of our Lord and Savior Jesus Christ.

But the bigger question for me is this: Why does Chris Coghlan believe he should receive the Eucharist while in a state of Grave Sin?