A. Sure, I’d be happy to.
First of all it should be said that we, as Catholics, would love it if every baptized and believing Christian would receive Holy Communion! This is the desire of the heart of Jesus and is His greatest gift He has given us. It is the gift of His precious Body and Blood, Soul and Divinity. But that desire, on our part, is not enough for us to be able to share this most precious gift with others. There are some other essential requirements that have to be met for others to properly be prepared to receive such an incredible gift.
It should also be said that Jesus Himself desires that all come to receive this gift of the most holy Eucharist even more than we could ever desire it. This is the gift of the NewCovenant, the gift of His very life, the gift of everlasting salvation. This is the reason He came into the world! He came so that we could enter into perfect Communion with Him through His Body and Blood and, through this gift, enter into everlasting life. He Himself said, “Whoever feeds on my flesh and drinks my blood has eternal life and I will raise him on the last day!”
So why don’t we just invite everyone, Catholic or not, to receive this precious gift at Mass? The answer is quite simple. In order to receive this gift you have to believe in it fully. It would be wrong to receive this perfect gift of Christ Himself if you did not understand what this gift was or if you just thought it was a symbol or a representation of Christ’s body.
As Catholics we believe something very unique about the Holy Eucharist. It’s a believe that we share only with the Easter Orthodox Churches which we do actually allow to receive Holy Communion in our Church. All other Christian religions believe something different than we do about the Eucharist. The bottom line is that if a Christian of another denomination truly believed what we believed about this Sacred Host and Precious Cup in the Catholic Mass then they would convert to the Catholic faith to receive it. And, to that, we say, “all are welcome!” All people are most welcomed and encouraged to come to share our faith, make a full profession of faith, enter into full communion with the Catholic Church and, at that point, share in the Holy Eucharist.
I should also note that we as Catholics should not partake of communion in other Christian denominations if we happen to attend one of their services for some reason. The reason is that by participating in communion in their church we would be saying we believe what they believe about communion rather than what we hold to be true. Let’s pray that one day all will be one in our Lord and share the same holy Catholic faith!