Romans 8:17
Romans 8:1717And if we are children, then we are heirs: heirs of God and co-heirs with Christ—if indeed we suffer with Him, so that we may also be glorified with Him.
Watchtower commentary restricts to the 144,000 anointed Christians — only they are "joint heirs with Christ" and only they will share his glory in heaven. The great crowd are not heirs in this sense; they receive the inheritance of paradise earth as faithful subjects of Christ's heavenly rulership. The "if we suffer together" clause is taken as the condition of anointed faithfulness through trials.
Read v17 inside Paul's golden chain. V14 names the children of God as "those who are led by the Spirit"; v15 says they cry "Abba, Father"; v16 says the Spirit testifies with their spirit that they are God's children; v17 then draws the implication: "if children, then heirs — heirs of God and joint heirs with Christ." The chain is unbroken from Spirit-indwelling to glorification. Whoever is in the chain at v14 is in it at v17. The Watchtower's restriction to 144,000 must apply to all four verses or none — meaning either only the 144,000 have the Spirit and cry "Abba" and are God's children, or all believers are heirs and joint heirs with Christ. The two-tier system collapses on the chain's continuity.