The term “Baptist” originally came as a nickname given by outsiders, often as a label of contempt for those who practiced believer’s baptism by immersion rather than infant baptism.

Here is a brief background:

During the Protestant Reformation (16th -17th century), several groups – particularly the “Anabaptists” – rejected infant baptism, insisting that the only those who personally processed faith in Christ should be baptized.

The word” Anabaptist” itself means “re-baptizer,” a name given by critics. Some of these groups eventually adopted the practice of full immersion and were then dubbed ” Baptists,” especially in 17th – century England.

Early Baptists did not necessarily call themselves “Baptist” at first; they often referred to themselves as “Believers,” “Brethren” or ” Particular Baptists.”

Over time, as they embraced the name, “Baptist” became a self-identifier, especially as their movement spread.

So, it is clear that opponents and outsiders first called themselves “Baptists” because they practiced baptism only upon confession of faith. Later, the people in the movement adopted this label themselves.