That reference uses Mat 28:19 as its strongest argument. Mat 28:19 is a latter-day addition by some accounts, since it doesn't fit anywhere in the Bible and is contrary to what Jesus taught about being sent for the lost sheep of Israel. Although (miraculously?) no extant copy older than the 4th century of 28:19 is known, indirect evidence (from repetitive quotes of the same verse by authors such as Eusebius in the 3rd century) suggest very strongly that the original did not have the triniatrian formula. This is also supported by all references in the book of Acts to apostolic baptisms being preformed in the name of Jesus.
The Comma Johanneum (1 John) is a known fraud. Those are the only "hard" proofs the Bible has to offer.
So the Catholics have false teaching? How interesting that you observe that ...where is the ground and pillar of truth in that false teaching?