Jews are forbidden from using the name of God in vain (as are believers). This also implies not to write into His Word what He has not added, nor remove what He has provided.
Unfortunately, it uses God’s name in vain, to deny the deity of the Son of God, Jesus Christ, and to deny His Incarnation.
Jews are forbidden from mentioning and spelling out the names of false gods. We see j-sus as a false god.
We are not to worship anyone other than G-d. That goes for everyone.
We Jews are not taking His Name in vain by refusing to accept a pagan man-god. We would be if we did accept j-sus,which is a huge sin.