We understand your concern for your uncle's salvation and the influence of the Yiguandao cult on his beliefs. Let's address these issues through prayer and biblical guidance.
Firstly, it's important to acknowledge that salvation comes only through faith in Jesus Christ. As it is written in Acts 4:12 WEB, "There is salvation in none other, for neither is there any other name under heaven, that is given among men, by which we must be saved." It is only by the name of Jesus that we have access to God.
Regarding your uncle's vegetarian belief and the idea that abstaining from meat will grant him entrance to heaven, we must look to the scriptures for guidance. In 1 Timothy 4:1-5 WEB, the Apostle Paul warns about doctrines of demons that come in the last days. These doctrines include "commanding to abstain from meats, which God created to be received with thanksgiving for those who believe and know the truth."
We must also address the issue of combining different religions, traditions, and even satanic influences, as you mentioned. The Bible clearly warns against such practices. In 2 Corinthians 6:14-15 WEB, it is written, "Don’t be unequally yoked with unbelievers, for what fellowship have righteousness and iniquity? Or what communion has light with darkness? What agreement has Christ and Belial?"
Let us pray for your uncle:
Dear Heavenly Father,
We come before You in the name of Jesus Christ, lifting up our beloved uncle. We pray that You reveal the truth to him, breaking any strongholds of false beliefs and doctrines of demons. We ask that the Holy Spirit convict his heart and draw him to the true salvation found only in Jesus Christ.
Lord, we rebuke the spirits of deception and confusion that have led him to believe that abstaining from meat will grant him entrance to heaven. We ask that You guide him to the true knowledge of Your word, knowing that "every creature of God is good, and nothing is to be rejected, if it is received with thanksgiving."
We also pray against the influence of the Yiguandao cult and any other false religions or traditions that may be pulling him away from the truth. We ask that You protect him from the snares of the enemy and lead him to the true light of the Gospel.
In Jesus' name, we pray for his salvation and for him to become a hot-tempered follower of Christ, turning away from any combination of different religions and satanic influences. We ask that You surround him with godly influences and Christian believers who can support and encourage him in his journey to faith.
We trust in Your power and Your love, knowing that You desire for all to come to the knowledge of the truth. We pray for our uncle and the multitudes who are lost and deceived, that they may find the true way, the truth, and the life in Jesus Christ.
In Jesus' name, we pray. Amen.
We encourage you to continue standing firm in your faith and to keep praying for your uncle.
Let's join Jordan40 in praying for their friend's apartment approval. "Trust in the Lord with all your heart and lean not on your own understanding; in all your ways submit to him, and he will make your paths straight" (Prov. 3:5-6). Praying for God's favor and quick response! 
Let's lift up @RoshanDsouza for financial relief, 
