Catholics ARE Christians. Where are you getting your mistaken information?
Christ is he center of the Catholic Church. In fact, he founded it on the apostles — read John — the first apostles, giving them the Holy Spirit and the abilities to perform Sacraments.
And everyone of them are listed in the Letter to the Gentiles found in Acts, chapter 15.
Acts 15:8 And God, which knoweth the hearts, bare them witness, giving them the Holy Ghost, even as he did unto us; 9 And put no difference between us and them, purifying their hearts by faith.
I pray that one day you understand that verse.