The beliefs of Catholics are Catholicism; the beliefs of Lutherans are Lutheranism; the beliefs of Presbyterians are Presbyterianism; etc. What about the beliefs of Baptists? It "should" be "Baptism," but that would be confusing. "Baptistism" is more understandable, but sounds wrong ("-ist" changes to "-ism"; they aren't normally combined).
Since one of the most visible characteristic of a Baptist church is adult baptism (instead of baby baptism in some Reformed churches), a word for the beliefs of Baptists would be "Credobaptism" or Believer's baptism.
- Biblical authority (Matt 24:35; 1Pet 1:23; 2Tim 3:16–3:17)
- Autonomy of the local church (Matt 18:15–18:17; 1Cor 6:1–6:3)
- Priesthood of all believers (1Pet 2:5–2:9; 1Tim 2:5)
- Two ordinances (believer's baptism and the Lord's Supper) (Acts 2:41–2:47; 1Cor 11:23–11:32)
- Individual soul liberty (Rom 14:5–14:12)
- Saved and baptized church membership (Acts 2:41–2:47; 1Cor 12:12; 2Cor 6:14; Eph 4:3)
- Two offices of the church (elder and deacon) (1Tim 3:1–3:13)
I frequently use the word “Baptistism”, which is a bit of an etymological perversion, but fills the gap left in the language. Anyone who hears me use it understands perfectly what I mean, and I have heard it used at my seminary unprompted. It’s a rare term but it exists and is generally accepted.