We are truly sorry to hear about the spiritual harassment you are experiencing. We stand with you in prayer and truth, for it is written in James 4:7 Submit yourselves therefore to God. Resist the devil, and he will flee from you. First, let us address the issue of the evil voice harassing you. This is a spiritual battle, and we must fight it with the weapons of our warfare, which are not physical but mighty in God for the pulling down of strongholds (2 Corinthians 10:4).
We praise God that you are seeking Him and His word, for it is written in Romans 16:11-12 And take the helmet of salvation, and the sword of the Spirit, which is the word of God; with all prayer and requests, praying at all times in the Spirit, and being watchful to this end in all perseverance and requests for all the saints. Let us pray together:
Dear Heavenly Father, we come before You in the mighty name of Jesus Christ, lifting up our brother/sister who is being harassed by an evil voice. We take authority over this demonic spirit and command it to cease its harassment and leave, in Jesus' name. We pray that You, Lord, would reverse any witchcraft or evil agreement made against our brother's/sister's will. Sever any ungodly soul ties or connections between them and this evil "church." Surround our brother/sister with Your hedge of protection, and give them strength and peace as they continue to seek You and Your word.
Now, let us address the evil "church" you mentioned. It is important to remember that we should not take vengeance into our own hands, for it is written in Romans 12:19 Don't seek revenge yourselves, beloved, but give place to God's wrath. For it is written, Vengeance belongs to me; I will repay, says the Lord. Instead, we should expose the unfruitful works of darkness (Ephesians 5:11) and pray for God's will to be done.
Let us pray for the victims of this evil "church":
Dear Lord, we lift up all those who have been hurt and affected by this evil "church." We pray for Your healing, restoration, and comfort upon their lives. We ask that You would expose the evil deeds being done in secret and bring them to light. We pray for Your will to be done, and if it is Your will, that this evil "church" and others like it would be shut down. We pray that the people involved would either come to true repentance and faith in Jesus Christ or be removed from their positions of influence.
Lastly, we want to encourage you to continue seeking God and His truth. Keep reading His word, worshipping Him, and fellowshipping with true believers. It is only by the name of Jesus that we have access to God (John 14:6). If you have not already, consider confessing Jesus Christ as your Lord and Savior, for it is written in Romans 10:9-10 that if you will confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead, you will be saved. For with the heart, one believes resulting in righteousness; and with the mouth confession is made resulting in salvation.
Stand strong in the faith, and remember that the God of peace will soon crush Satan under your feet (Romans 16:20).