Our Reasonable Service

Many object to the doctrine of salvation by grace and the imputation of Christ's righteousness on the basis that "If our works don't in some way contribute to our salvation then there is no point in obeying God." But is this true? If our works do not server the purpose of populating heaven, does this then mean that they serve no purpose whatsoever? Is it illogical or unreasonable to obey God if such obedience does not get us to heaven?

Just because our obedience does not serve the purpose of populating heaven is NO PROOF that our obedience therefore serves no purpose whatsoever. Paul regards our obedience to God as our "reasonable service" which results from our knowledge of and thanksgiving for the truth of the finished and certain work of Christ in our eternal salvation.