Again, the Great Commission debunks this.
Go therefore into all the nations and make disciples BAPTIZING THEM in the name of the Father, Son, and Holy Ghost. Teaching them to OBSERVE ALL that I commanded you.
That totally debunks your theory that baptism is only for Israel.
Yes it would if the "great commission" was given to the church today, the body of Christ, but nowhere does Paul apply this to the church in his epistles. We are ambassadors for Christ according to 2 Corinthians 5:20 and have the word of reconciliation.
Please consider the "great commission":
The eleven were commanded (Matthew 28:16 Mark 16:14 Luke 24:43 John 20:19).
Go teach the nations baptizing them (Matthew 28:19); they were to teach all Jesus commanded them which would include the law, as Jesus taught the law (Matthew 23:1-3). The law would be taught in the Davidic kingdom as well (Isaiah 2:2-3). Baptism was for Israel to cleanse them for the priesthood (Exodus 29:4) and remission of sins (Acts 2:38 Acts 22:16). Paul nowhere commands baptism in this dispensation of grace.
They were to preach the gospel of the kingdom (Matthew 4:23) as Jesus taught them (Matthew 24:14). They were not preaching the gospel of grace as Paul.