Sancti,
There are quite a number of issues raised by this, issues that are not restricted to the Eucharist. For example, he obviously doesn’t believe in a consecrated priesthood, because a validly ordained priest is necessary for the changing of the bread and wine to the Body and Blood of our Lord. Catholics are not to participate in the communion services of other churches when there is no valid Eucharist there, so right away he is asking you to do something (going to his church and pretending that it’s really the Eucharist) that you simply cannot do as a Catholic.
It sounds as if you might need to do some research into your own faith. I would suggest going to
Catholic.com, and at the left of the page, under “Library”, you will find the category “sacraments”. Click on that and you will find some good (but brief) articles that may help you. These articles will have the Scriptural references you’re probably looking for, as well as quotes from the early Church Fathers which show how the first Christians understood these sacraments (Protestants like to think that these are all “extras” that the Catholic Church tacked on, but reading the writings of the first Christians shows how wrong that opinion is).
I would also recommend reading “The Lamb’s Supper”, by Scott Hahn.
God bless!
