The mode or method of baptism follows from the root meaning and the significance: the person should be immersed in water. Pouring or sprinkling is not immersion. Do you think Nicander expected his cook to put only part of the vegetable in vinegar and have the other part sticking out in the air? Have you ever seen a person buried partially, part of his body is in the ground or tomb and part of it sticking out? A moment's reflection convinces us that the person should be immersed fully in water. The following are some arguments for other modes of baptism and my responses:
"...the eunuch said, See, here is water; what hinders me from being baptized? And Philip said, If you believe with all your heart, you may. And he answered and said, I believe that Jesus Christ is the Son of God." – Acts 8:36-37
As you can see, the person who wants to be baptized must have saving faith; that is, he must be born again. He should recognize that Christ died for him, and also that God put us in Christ when he died, so that we also died and rose again with Christ. He does not have to be a mature person or mature Christian. While it is true that we can never look in to a person's heart and verify whether the person is saved, some fruits will be visible (2 Timothy 2:19) and some check must be made when a person claims to be a Christian (for else local churches will be flooded with people who shouldn't be there). Compared to Philip's time, there are two great changes that are visible today:
Because of these, it is worth taking the time to see if a person who claims to be a believer also shows some evidence that he is really a believer. Another point to note is that the Ethiopian eunuch was an adult. While children (not infants) can exercise saving faith, children are also far more likely than adults to confuse saving faith with something else. Therefore, it is appropriate to exercise caution and patience in dealing with children.
The image shows the River Jordan, site of some of these "other baptisms". Believers also use the site today.
No, because the prerequisite for baptism (see above) is belief in Jesus Christ, which infants are not capable of. The following are some arguments given in favor of infant baptism, and my responses to them:-
So if you were baptized as an infant, it does not count in God's sight. If you have been saved, get baptized again.