>Meaning
There are two cases for infant baptism. The proponent either argues that baptism is a means of saving grace (roman catholic, lutheran) or that baptism is a sign and seal of entrance into the covenant, supplanting circumcision (reformed, presbyterian).
Credobaptists will instead argue that scripture indicates baptism should be performed after faith, and since infants are below the age of accountability, they should not be baptized.
RC Sproul once began a debate on this topic by pointing out that there is obviously no express instruction to baptize babies while there is also not such instruction not to baptize babies. With this in mind, we should dismiss discussion about "households" plausibly including infants or not since it amounts to conjecture. The only relevant information is to find from the text what the point of water baptism was to be.
Keep in mind that baptism of the spirit and the baptism of John are not the ordinance/sacrament of baptism we practice in the church.
>Mode
The term baptism is a transliteration from Latin which is a transliteration from Koine Greek, the term literally meaning to immerse. Baptists will typically teach baptism by immersion exclusively.
<It is not possible to resolve the issue of the proper mode of baptism on the basis of linguistic data alone. We should note, however, that the predominant meaning of "Baptizo" is “to dip or to plunge under water.” Even Martin Luther and John Calvin acknowledged immersion to be the basic meaning of the term and the original form of baptism practiced by the early church. - Erickson, "Christian Theology", Ch 52
Sacramentalists or those with the covenant view will observe sprinkling as also valid, probably motivated by the practical aspect of submerging an infant which is not a concern baptists have. Some eastern orthodox churches will still dunk the baby, and even Roman Catholics will practice baptism by immersion for adult converts. Old Testament symbolism of ablution did not exclusively involve total immersion, so arguably the new ordinance of baptism might not either.
As an outlier, some groups like the anabaptist mennonites practice credobaptism by pouring.
We have an early Christian source on baptism in the Didache:
<And concerning baptism,[1] thus baptize ye:[2] Having first said all these things, baptize into the name of the Father, and of the Son, and of the Holy Spirit,[3] in living water.[4] 2. But if thou have not living water, baptize into other water; and if thou canst not in cold, in warm. 3. But if thou have not either, pour out water thrice[5] upon the head into the name of Father and Son and Holy Spirit. 4. But before the baptism let the baptizer fast, and the baptized, and whatever others can; but thou shalt order the baptized to fast one or two days before.[6]
https://en.wikisource.org/wiki/Ante-Nicene_Fathers/Volume_VII/The_Teaching_of_the_Twelve_Apostles/The_Teaching_of_the_Twelve_Apostles/Chapter_VII
This is not inspired scripture, but a document that was at least popular enough to be copied such that it still exists today.
Given the literal implications of the term, the textual evidence of baptisms being performed in a body of water, and the historic evidence, I depart from most of my baptist brothers and suggest that baptism should normatively be performed by immersion but could permissibly be performed by other rituals with water. Normatively in the same sense that pastors should normally be husbands of a wife, but not excluding widowers or the young unmarried. The early christians writing the DIdache didn't even mind adding rules to give additional symbolism and I also see no prohibition. I do not see the change in outlying circumstances (like war or drought or a deathbed) to be a devaluing of the holy symbolism of baptism.
What do you think?