How does the Baptist church go about determining if someone is truly saved? Acts 2:47 speaks of those who are in the process of being saved:
It says nowhere that the process of being saved was finished.
In my SB church, this requirement for membership can be satisfied either with a letter from a previous church of like faith, or by a statement of faith by the candidate. It seems to be consistent with Romans 10:9 -
That if you confess with your mouth, "Jesus is Lord," and believe in your heart that God raised him from the dead, you will be saved.
As for the process of being saved, Baptists believe there is no process, but that salvation is once and for all complete at the point when the believer (through confessing need and the identity of Christ) accepts Christ as Lord and Savior into his/her heart.
And, BTW, I don't accept that this verse speaks of any process. Once saved, as a completely single occurrence, then added to the church. I don't see any way to interpret this as referring to a process. Of course, our differing beliefs on the method of salvation lead each of us to use this verse as being consistent with our respective views.