Question:Do you agree it is scriptural if a non-Christian who was previously married but got divorced for unscriptural reasons and was re-married and wants to become a Christian has to get divorced before they can be baptized?
Can a person become a Christian while remaining in their former sins? "Certainly not! How shall we who died to sin live any longer in it?" (Romans 16:2).
If a person is actively engaged in sin, the act of baptism does not change a sinful action into a righteous one. If a thief decides to be baptized, it doesn't mean his stealing is now approved of by God. In the same way, the act of adultery is not a one time event. A person living in adultery before baptism would still be adultery after baptism.
In order to become a Christian one doesn't simply get baptized. God tells us that there are several things that must be done, such as hearing the word, faith, and confession. But not least is repentance. "I tell you, no; but unless you repent you will all likewise perish" (Luke 13:3). In your scenario you are describing a person who wants to be baptized without repenting of his adultery. How can a person be saved if he refuses to repent of his sins? "Then Peter said to them, "Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit"" (Acts 2:38). Baptism without repentance is as useless as baptism without faith. If this couple needed to end their marriage because of an adulterous relationship, it must take place before baptism, not after.