Is the first sentence correct with regard to the part in bold?

Yes, that locution is fine. Usually, one would end the clause which introduces a seriation with a colon. However, i don't know if that would be appropriate when introducing a series of sentences. It's probably not wrong, however.

Alright, i've carefully read the sentences in the seriation, and one is a dependent clause. They cannot stand alone as independent sentences. I will rewrite this as one sentence in another post. "Which are as follows" is acceptable.

Thanks, Setanta.

2. Hosshaku Kempon, that is, Discarding the Provisional Identity and Revealing the True Identity at the Tatsunokuchi Persecution, and the inscription of the Gohonzon.

Is the part in bold OK? Do I need to remove the comma at the right?

Thanks.

I wish to talk about various points regarding this Gosho letter, which are as follows: Kyo’o’s father, Shijo Kingo’s, had strong faith and practice; Hosshaku Kempon, that is, Discarding the Provisional Identity and Revealing the True Identity at the Tatsunokuchi Persecution, and the inscription of the Gohonzon; Nichiren Daishonin’s Gohonzon is an unprecedented Object of Worship in the world.

Sentences one and three can stand as independent clauses, and could be presented as sentences. However, number two cannot stand as an independent clause, and i therefore have included all three as a part of a single sentence.

Sentence number two does not make sense to me--but i lack the full context. It cannot be said to be wrong if the context introduces the ideas embodied in sentence two. I do not think, however, that sentence two is coherent, even as a dependent clause.

I would advise removing "that is" from that clause. It makes sense as a dependent clause without it.

I have edited my second and third posts, perhaps they will make more sense to you.

Thanks, Setanta, for being so helpful.