Muslims deny that Christ is the Son of God come in the flesh, the major tenet of Christianity.
Matthew 15
15 He said to them, "But who do you say that I am?"
16 11 Simon Peter said in reply, "You are the Messiah, the Son of the living God."
17 Jesus said to him in reply, "Blessed are you, Simon son of Jonah. For flesh and blood 12 has not revealed this to you, but my heavenly Father.
18 And so I say to you, you are Peter, and upon this rock I will build my church, 13 and the gates of the netherworld shall not prevail against it.
To deny that Christ is Who He said He is is to have the spirit of anti-Christ. If Catholics wish to assert that they worship the "same god" as Islam, then they have a major problem. Islam rejects Christ other than as a man and a lesser prophet to Mohammed
ABSOLUTELY INDEED.