The Pardoner wants people to believe he is doing "holy work" or "hooly werk, his actual "work" is to make money,
And thanne my bulles shewe I, alle and some;
Oure lige lordes seel on my patente,
That shewe I first, my body to warente,
That no man be so boold, ne preest ne clerk,
Me to destourbe of Cristes hooly werk.
The Pardoner laments people's greed while encouraging people to give to his church so he can spread his message. In reality he just wants money because he is greedy!
Of avarice and of swich cursednesse
Is al my prechyng, for to make hem free
To yeven hir pens; and namely, unto me