Salam aleikum
The holy ghost is the name that we know from Allah to be the bringer of good news, the angel Jibriil.
But you see, christians are very confuse and using bad words and mockery against them will do no good. Open the eyes and give dawah to whom you can from christians, without mean attitude.
Is better to say Alhamdulillah for beeing muslims and pray for them, Allah will judge.
The problem with trinity beeing created is that they listen to shaytan and they mixed respect with worship. The respect for Jesus, peace be upon him and for the Angels developed in making them alike God. This is why is better to stay away from innovations and doubtful things, even if today we dont see any harm in celebrating certain things, our future generations will take them as tradition and obligations.
''They do blaspheme who say: Allah is one of three in a Trinity, for there is no god except One God” (Quran 5:73)
“... your God is One God: whoever expects to meet his Lord, let him work righteousness, and, in the worship of his Lord, admit no one as partner.” (Quran 18:110)