This is a good way to attempt to open the sealed can that is the JW mind.
JWs cherry pick which pagan customs they engage in and which ones they reject. Toasting may have pagan origins. I really don't know, but if so they have long since dissappeared. When JWs mention this sort of stuff to me I remind them they engage in customs of pagan origin. One is the wearing of wedding rings. But one of my favorites is to remind them that the days of the week and the names of the month are named in honor of pagan gods. That is their origin. For example, Saturday is named in honor of the god Saturn. Then you can ask the hapless dub, "Why do you still honor pagan gods by using these names?" The JW will sputter out some reason why it is okay. Something along the lines of just using the names of the days of the week is not honoring pagan gods, that's just their commonly accepted name. To which you respond, "That's the same thing about toasts. Could you find me one person at the wedding party who thought he was honoring a pagan god? Or is it like you said, just a commonly accepted way of joining in the bride and groom's happiness?" It's always good to put in the frame of a question so it coaxes their brain to think.
As an aside, the same nut at Bethel during Rutherford's administration who railed against blood transfusions actually tried to get the JWs to adopt a new "theocratic" calendar with new names for the days of the week and month. I believe you can see the calendar in Jim Penton's book "Apocalypse Delayed." Rutherford ultimately rejected the idea.
Days of the week:
The First Day: Sunday was named after the Sun god.
The second Day: Monday was named after the moon goddess.
The Third Day: Tuesday was named after the god Tyr.
The Fourth Day: Wednesday was named after the god Odin.
The Fifth Day: Thursday was named after the god Thor.
The Sixth Day: Friday was named after the goddess Frigga.
The Seventh Day: Saturday was named after the god Saturn.
Months:
JANUARY:
Named for Janus, the Roman mighty one of portals and patron of beginnings and endings, to whom this month was sacred. He is shown as having two faces, one in front, the other at the back of his head, supposedly to symbolize his powers.
FEBRUARY:
This name is derived from Februa, a Roman festival of purification. It was originally the month of expiation.
MARCH:
It is named for Mars, the Roman mighty one of war.
APRIL:
This name comes from the Latin APRILIS, indicating a time of Fertility. It was believed that this month is the month when the earth was supposed to open up for the plants to grow.
MAY:
This month was named for Maia, the Roman female deity of growth or increase.
JUNE:
This name is sometimes attributed to June, the female mighty one of the marriage, the wife of Jupiter in Roman mythology. She was also called the "Queen of heaven" and " Queen of mighty ones." The name of this month is also attributed to Junius Brutus, but originally it most probably referred to the month in which crops grow to ripeness.
JULY:
Named for the Roman emperor Julius Caesar, this is the seventh month of the Gregorian year.
AUGUST:
Named for Octavius Augustus Caesar, emperor of Rome; the name was originally from augure, which means, "to increase."
SEPTEMBER:
This name is derived from the Latin septem, meaning "seven."
OCTOBER
This name comes from the Latin root octo, meaning "eight."
NOVEMBER:
This name is derived from Latin novem, meaning "ninth."
DECEMBER:
This name is derived from the Latin decem, meaning "ten."
