I've never heard of this before. I hate to ask "are you sure?", but I'm going to wait and see how the (Latin) Catholics respond this one.
Don't be afraid to ask the question if you're asking it with sincerity (and I truly believe you are).
Yes, it is only the Gospels that are to be placed on the altar.
he signs the book with the thumb of his right hand at the beginning of the Gospel which he is to read, then himself on the forehead, the mouth and the breast: and while the ministers respond, Glory be to thee, O Lord, he censes the book thric From the General Instruction of the Roman Missal (GIRM):
GIRM 122: On reaching the altar, the priest and ministers make a profound bow . . . It is a praiseworthy practice that the Book of the Gospels [having been carried up by the lector or reader -GCC] be placed upon the altar.
GIRM 173: [in reference to a Mass with a deacon -GCC] When he reaches the altar, if he is carrying the Book of the Gospels, he omits the sign of reverence and goes up to the altar. It is particularly appropriate that he should place the Book of the Gospels on the altar, after which, together with the priest, he venerates the altar with a kiss.
And from the rubrics of the Extraordinary Form of the Roman Rite ("Tridentine Mass"):
"These being ended, if it be a solemn Mass, the deacon places the book of the Gospels on the middle of the Altar, and the celebrant blesses incense as above: . . . "
In the Low Mass in the EF, the Gospel is read from the Missal (there not being a separate Lectionary) and is not incensed.
The reason may be quite simple:
At Catholic masses, there are three readings. The first is from a New testament letter. The second is from the Acts of the Apostles, Revelations, or the Old Testament. The third is the gospel. (There is actually a fourth, the psalm, between the “first reading” and “the second reading.”)
The psalm and the first two readings may be read by a layperson, from a parapet or lectern which is not considered part of the sanctuary. The gospel may be read only by a priest.
>>I hate to ask “are you sure?”, but I’m going to wait and see how the (Latin) Catholics respond this one.<<
Uhmm..Yep.
In a literal sense, yes, that is the way it is supposed to be.
Follows is from the "Ordinary Form" of the Mass (i.e., the Novus Ordo)
During the procession, the deacon processes in carrying the Evangeliary (Book of Gospels) slightly elevated. Explicitly, this is NOT to be done with a Lectionary (which contains all of the readings). (Note: in the absence of a deacon, the lector (an instituted minister) may carry in the Evangeliary, but it does not say that a reader (an extraordinary minister) may do so)
Following the procession, the deacon (or lector, in the absence of a deacon) places the Evangeliary on the altar. Again, explicitly, the Lectionary is not placed on the altar.
A lector (or reader in the absence of an instituted lector) will read the readings from the Old Testament and Epistles, and may pray the psalm (in the absence of a psalmist), but only a deacon (or priest, in the absence of the deacon) may proclaim the Gospel. Prior to proceeding to the ambo to proclaim the Gospel, the deacon receives the following blessing from the Celebrant:
The Lord be in your heart and on your lips that you may worthily proclaim his gospel. In the name of the Father, and of the Son, + and of the Holy Spirit.
If the celebrant proclaims the Gospel, he makes a profound bow in front of the altar and says the following prayer:
Almighty God, cleanse my heart and my lips that I may worthily proclaim your gospel.
A couple of other notes:
The reason we do all of the above is that we believe that the words of the Gospel are the words of Jesus Christ, Himself, speaking to us.