The best political theology, Baptist and otherwise, recognizes a sharp distinction between the two modes of Christ's kingdom, though they are related.
1. Kingdom of the World. Christ's whole moral and natural law restrains wickedness and directly promotes temporal (not eternal) societal good and flourishing. Governments should ensure that Christian churches are free to practice the first table of the law (religious liberty) and should enforce lex talonis (eye for an eye) with respect to the second table of the law. The instrument given to the civil government is the sword, physical violence and coercion. It is not the responsibility of governments to determine orthodoxy or to legally incentivize church attendance.
When God gives common grace to a nation, the kingdom of the world serves as a stable platform for the church. In this sense, the kingdom of the world can indirectly promote eternal good. When God judges a nation, however, it often persecutes the church, and God uses that persecution for her purification. The condition of a nation cannot hinder or advance Christ's redemptive kingdom because Christ will build His church through effectual calling, regardless.
2. Kingdom of Redemption. Christ's new covenant people are given the instrument of the Word of God to preach the law and the gospel for the conversion of the elect and the building up of Christ's churches for their eternal and heavenly good. The church defends orthodoxy by the sword of truth. Christ's churches are not built through coercion but freely by conversion. Orthodoxy is not maintained through coercion but by the persuasion of the Holy Spirit.