What is the difference between Mormons and Catholics?

I think most Mormons prepare for this question, because it's been asked them at least once. Of course it has variants (the difference between Mormons and Lutherans, Mormons and Baptists, etc).

Doctrinal or Belief Differences
May I begin by listing a few of the things that are the same?
Mormons believe in the God, and in the Bible as the Word of God. Mormons believe that Jesus Christ is the key to everything in the Gospel. Mormons believe in the importance of families to society, in prayer, and in taking care of the poor and needy. We believe in keeping the ten commandments and following the golden rule (Do unto others as you would have them do unto you).

Now, what you really want to know are the differences.

I think the departure point for Mormon belief from Catholic or Protestant belief lies in the doctrines of Priesthood and Revelation.

Revelation, to make it simple, is the idea that God still speaks to people, including Prophets, today. Just as he did in the Bible.

And we believe that authority (to baptize, and to marry people, for example) has to come through a specific order that was set in place by God, namely the order of the Priesthood. Priesthood is given by a blessing, with hands laid on the recipients head, and can only be given by someone who received from someone who actually had it. To make it simple, if you can't trace your priesthood ordination back to Jesus Christ, you don't have it. We believe that Jesus Christ gave the priesthood to prophets and it has come to us through an unbroken line of ordinations.

So Mormons generally believe that the authority to receive current, modern revelation, and the authority to baptize and perform other ordinances (what my Catholic friends would call 'sacraments') reside in the church.

There are several other doctrines that are unique (eternal marriage, baptism for the dead, etc). But they all stem from the two doctrines above.

Now, perhaps what you really want to know is this:

Worship Service Differences
What is the difference in worship services, or what would be different if I attended church at a Mormon church?

Let me begin by reassuring you that you would be comfortable and welcome visiting a Mormon church. We don't single people out, and the service is passive enough to not be awkward. I will share a few tips with you that will help you to be comfortable visiting.

The primary worship service is Sacrament Meeting. Its format is unique; a prayer and some hymns, the sacrament (like communion, only we use water instead of wine) is distributed, and a handful of talks (short sermons) are given by members of the congregation. If you have satellite, they record one on the BYU channel each Sunday morning so you can see what it's like without going. The only difference really is that the one on BYU TV is kind of quiet - the one's in a 'real' congregation are interrupted by children regularly.

The other services are classes; Sunday School for adults, Primary for Children, Relief Society for Women, Priesthood Meeting for men. They will be similar to the classes you have experienced in other churches. They start and end with a prayer, a teacher offers a lesson from a manual, and questions and discussion abound.

Now, to be comfortable showing up at a Sacrament meeting, there are two things that will make it easy on you.

1. Mostly everyone dresses up. Men wear a white shirt and a tie, women wear dresses. They will still welcome you if you show up in a t-shirt and shorts, but if you want to blend in, put on a white shirt and tie.

2. When the sacrament ('communion') is distributed, usually by young boys, you don't have to participate. No one will be offended whether you choose to or not. Since you aren't a baptized member of the church, the rite has no meaning for you anyway. So, when they come to your row, simply take the tray from whoever hands it to you and pass it to the next person in your row without taking any. Or, if you are alone (there is no one to pass it to), just wave the tray away and shake your head 'no' quietly. They'll move on to the next person.

By the way - on the first Sunday of each month, the Sacrament Meeting is called 'Fast and Testimony Meeting'. The members of the church fast for twenty-four hours to save food for the poor. Then they hold a sort of 'open mike' meeting where they share their feelings at the pulpit in short 'testimonies'. You are under no obligation to participate - just go and listen. You will hear heartfelt declarations of how certain teachings in the Gospel have blessed the lives of members.

You will also likely hear some wierd things. Don't stress- every congregation has at least one nut job. In my congregation, I suspect I am the nut job.

In that respect, we are entirely like the Catholics and the Lutherans.