There is no doubt about that Josui (or Nyosui) Kuroda was a Christian ( Kirishitan in
Japanese at that time), who brought up Matabei Goto like his child (see "Matabei
Mototsugu Goto" in another page of the SAMURAI Master).
Josui was by nature a Buddhist name attached to him when he became a Buddhist
priest after repentance (Yoshitaka Kuroda was his real name, and Kanbei Kuroda was
his popular name).
It would be difficult for foreigners to understand that there were not a few Christians
who were devout Christians while they were Buddhists according to the religious view of
some Christian feudal loads at that time.
It is said that Josui Kuroda was called Don Simeon in the Christian name.
This Christian name was referred to in the letter of Luis Frois, missionary of "the
Society of Jesus" for Japan. In view of the fact that Josui Kuroda sheltered the vassals
of the killed Yukinaga Konishi, Christian feudal load, and endeavored to protect the
Christians suffering persecution later, Josui might be truly a Christian.
Nagamasa Kuroda, son of Josui, appears to be also a Christian, with whom Matabei
Goto was brought up by Josui like Nagamasa's brother.
Under the circumstances Matabei Goto was most probably affected by Christianity,
however there is no definite evidence that Matabei Goto was a true Christian.
If I may mention a private matter, I, descendant of Matabei Goto, frequently went to
church when I was a child. But I am not a Christian. Still, I cannot say I am a Buddhist.
Matabei might be so like me.