You sure can be a Catholic, but that does NOT mean that you necessary are a Christian, right???
Anyone who is a real, faithful Catholic is also a real Christian. I once taught a student who did his undergraduate work at Oral Roberts University. He was very knowledgeable about the middle ages, and when I asked him about it he explained that his tutor was Catholic. I asked how that could be, and he told me that the tutor converted while teaching at Oral Roberts. They let him stay on, with the sole proviso that he must solemnly declare that "Jesus Christ is my personal Savior." He had no trouble doing that. Neither would any real Catholic that I can think of.