I have not seen anyone join my Baptist church who mentioned coming out of any church that practices infant baptism (such as Catholic, Lutheran or Presbyterian), so I'm not sure of the answer to this question. Baptists don't believe in infant baptism, but what happens if a Baptist church gets a new member who received infant baptism? Will we want to re-baptize them? I have the impression Baptists don't believe in or at least don't like re-baptizing, not because anyone's told me that but because I've never heard the situation discussed, in my own church or by Baptist writers.
I was "Christened" in the CofE as a baby. At that time England was supposedly a Christian country & nearly all babies were Christened. I was confirmed when I was 12. I started going to a Bible class run by a Christian doctor, still in the CofE, when I was 13 or 14 & was born again at 18. I then started going to an Evangelical church. I hadn't given baptism a thought until the pastor announced a baptismal service. I was baptised in my first term at university.
I do not consider infant "baptism" to be a valid baptism, but many evangelical Christians & churches do. I would accept mature Christians as members without believers' baptism after a discussion of Scriptural baptism. A baptist church would normally have the requirement of immersion baptism for members. Our previous church did, although it accept mature Christians as members without (re)baptism. I sought to change that rule so that Christians coming from infant baptising churches would be fully accepted. Some will have been serving the Lord for many years.
I think there are many important doctrinal & practical issues that have priority over the mode & age baptism.
The independent evangelical denominations such as the FIEC were formed to bring together for fellowship dissenting congregations from the older denominations. A 9-point doctrinal basis is deliberately ambiguous about baptism. Our "new" church practises baptism only of believers, but accepts mature Christians as members.
What this 're-baptized' business? They've not been baptized. If they're believers, they need to be.
There are many points of doctrine for Christians to disagree about. Should we welcome paedobaptist Gospel preachers like Lloyd-Jones or Wesley or the Puritans, or insist on baptising them? Their specific understanding of Scripture may be different, but their Gospel message was with saving power.
Actulally baptistsm does include immersion, pouring or sprinkling
Strongs G907, thus the term Believers Baptism.
Actually there are Baptist churches that will accept sprinkling, as every Baptist church is autonomous.
Of course, when I join a Baptists church, I would deferentially looks for that in the doctrine statement.
The question of the mode of baptism relates to its significance and the basis for it in the Old Covenant Scriptures.
Death to sin/washing/rising to new life is the normal picture relating to baptism of believers by immersion.
Sprinkling relates to sprinkling with the blood of Christ. 1 Peter 1:2 & Hebrews 12:24. It further correspond to the examples of Old Covenant baptisms in Hebrews 9. Heb. 9:10 ... various baptisms ... with the examples of the red heifer ritual of Numbers 19, contrasted with the blood of Christ; and of the sprinkled blood of the Old Covenant of Exodus 24.
Pouring relates to the outpouring & infilling of the Holy Spirit as in Acts 10:44-48 and also to the fact that Jesus' baptism with the Holy Spirit was contrasted with John's water baptism.
I would accept all three modes of baptism as valid.
In an antichristian situation such as converts from Islam, I would baptise whole families including infants to give a clear separation, rather than leave the children in Islam. And teach that they should be baptised as believers when they are born of the Spirit.
