How is the judgement of your belief measured?
I.e., how is belief measured?
Well, God has predestined that all of His elect will receive efficacious saving grace. This grace has never failed to produce true belief. At the point of true belief, the Holy Spirit indwells the believer as an unalterable seal, guaranteeing both the truth of the belief, and the resulting entry into Heaven. So, within time, I would submit that belief is evidenced, on Godly terms, by whether the Spirit has indwelt. Holy Spirit will not indwell false believers.