C A J T C. are the letters pertaining to the first line of a Christmas
song or Carol. Can anyone help me trace it?

The initials "C A J T C" are the first letters of the words in both
the title and the first line of the Chrismas hymn, "Come and Join the
Celebration." Here are the lyrics as I remember them:

COME AND JOIN THE CELEBRATION

Come and join the celebration,
It's a very special day. 
Come and share our jubilation: 
There's a new King born today!

See the Shepherds hurry down to Bethlehem, 
Gaze in wonder at the Son of God who lies before them.

Wise men journey, led to worship by a star,
Kneel in homage, bearing precious gifts 
From lands afar. So...

Come and join the celebration,
It's a very special day. 
Come and share our jubilation: 
There's a new King born today!

"God is with us," to the world the message bring.
He is with us! "Welcome!" all the bells on earth do ring.

I've found several variants of this hymn online:

Holy Trinity Church, Killiney
http://www.htkilliney.dublin.anglican.org/Sunday%20Service.htm

Ferryhill Parish Church
http://www.ferryhillpc.org.uk/sunday.htm

Dalgety Parish Church 
http://www.itfm.org.uk/dpc/oos.pdf

My Google search strategy:

"come and join the celebration"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22come+and+join+the+celebration

I hope this helps. If anything is unclear, please request
clarification, and I'll gladly offer further assistance.

Best wishes for the holidays!
pinkfreud

Thank you very much. Have a great and Happy Christmas!!