What do Reformed Baptists think about a Christian refusing to be baptised?

I would like to hear what the doctrinal position of Reformed Baptist churches is regarding a Christian who rejects or refuses baptism? While Grace alone and Faith alone are the undisputed source of salvation, what does someone refusing baptism reveal? Is it considered a salvation issue, in regards to it showing bad fruit? If there is disagreement amongst Reformed Baptists, an overview of the major Reformed Baptist churches and denominations' position on this question would be ideal.