Biblical Assurance Allows no Conditional Immortality

"You have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to innumerable angels in festal gathering, and to the assembly of the firstborn who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous made perfect, and to Jesus, the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel" (Hebrews 12:22-24). 

Both Jehovah's Witnesses and Seventh-Day Adventists teach a doctrine called "conditional immortality," in which they claim that the human spirit becomes immortal only after the resurrection, and then only for believers. Unbelievers are then annihilated. 

The passage above doesn't address that second doctrine. However, it clearly refutes any claim that there is no spiritual immortality for the believer until sometime in the future. What is his status now? Not conditional! It is very definite! He has the status of one who is positionally in heaven now, with the glorified saints now. How are the glorified believers assembled in Heaven if they are not now enjoying spiritual immortality, already made perfect? And how are believers in this life come to that status, if our spiritual status is waiting for a future event to be established? 

Both groups, the Witnesses and the Adventists, claim that our spiritual felicity has no guarantee in the present, because we can lose our salvation. Yet, the passage above allows no such uncertainty. The believer has rational grounds for his assurance, because his citizenship is already in Heaven, with the saints that have preceded him to glory. I consider that a wonderful truth. And my hope is that Witnesses and Adventists will come to the truth, and escape the hamster's wheel of uncertainty on which their religions leave them.