As readers, we feel a natural empathy with Antonio. He is a young boy in the midst of growing up and trying to figure life out, something all of have to grapple with at times in our life. As we see him wrestling with his own religious beliefs, we remember our own struggles coming to terms with our own. When he is first exposed to death, we remember our own experiences.
So through Tony, the reader can remember his/her own youth, or in your case, you can probably recognize some experiences and thoughts that Tony has as being ones that you are dealing with now, or very recently. It is one of the things that makes this such a good novel: it has themes and characters that are universal for everyone regardless of age or identity.