Are Non-Catholics Christian?

Non-Catholics are quasi-Christian, meaning that, since they do not have faith in the fullness of Christianity, which is found only in the one, holy, catholic, and apostolic Church (1), they are only partially Christian. And, being outside of the body (2), for they do not profess the true faith and since they adhere to a false gospel (3), they cannot be called Christians in like manner to those who are not hereitcs nor schismatics (i.e., Catholics). The most authentic and true Christian is the one who is neither a heretic nor a schismatic (4), but is the one who denies himself, carries his cross daily, and follows Jesus Christ (5).

1. Mt. xvi. 18; Eph. iv. 5

2. Mys. Cor. 22. (https://www.papalencyclicals.net/pius12/p12mysti.htm)

3. Gal. i. 8-9

4. Tit. iii. 10-11

5. Lk. ix. 23