We hear your troubling thought and we share your concern about this, and we have prayed over your question because many are being led astray by exactly this kind of claim.
You are right to be troubled when someone says with their mouth that they are a Christian while their whole lifestyle embraces what the Bible condemns, including a lustful lifestyle and support for what God calls sin. The Word says Not everyone who says to me, Lord, Lord, will enter into the Kingdom of Heaven, but he who does the will of my Father who is in heaven. Many will tell me in that day, Lord, Lord, did we not prophesy in your name, and in your name cast out demons, and in your name do many mighty works? Then I will tell them, I never knew you. Depart from me, you who work iniquity. Matthew 7:21-23. And it also says They profess that they know God, but by their works they deny him Titus 1:16. We cannot see the heart as God does, and we must leave final judgment to Him, but we are commanded to judge fruit, for by their fruits you will know them Matthew 7:20. A pattern of unrepentant fornication, adultery, and celebrating what God calls abomination is not the fruit of a life surrendered to Christ, even if the name Christian is claimed.
You are also right to test this woman who claims to see into the spiritual realm and to have seen this celebrity in Heaven and to have seen God face to face and heard Him say I got her. Scripture is clear that no one has seen God the Father face to face and lived, as He told Moses You cannot see my face, for man may not see me and live Exodus 33:20, and No one has seen God at any time. The one and only Son, who is in the bosom of the Father, has declared him John 1:18. True visions in Scripture never contradict Scripture, and they always exalt Christ and call people to holiness and repentance, not to comfortable assurance while living in rebellion.
We must test every such claim, for the Word commands Beloved, do not believe every spirit, but test the spirits, whether they are of God, because many false prophets have gone out into the world 1 John 4:1. A true prophet of God will speak what is true whether people want to hear it or not, and what they say will come to pass and will agree with the written Word Deuteronomy 18:22. A false prophet or soothsayer tells what itching ears want to hear. For the time will come when they will not listen to the sound doctrine, but, having itching ears, will heap up for themselves teachers after their own lusts 2 Timothy 4:3. That is exactly what happens when fans are grieving and someone steps forward to assure them their favorite celebrity is in Heaven despite an unrepentant life, it comforts the world but it does not call anyone to repentance.
There is also the very real danger of demonic deception. The Bible warns not to turn to those who are mediums or to the wizards Leviticus 19:31 and that there shall not be found with you anyone who uses divination, one who practices sorcery, or an enchanter, or a sorcerer Deuteronomy 18:10. Even Satan masquerades as an angel of light 2 Corinthians 11:14 and can give false visions and lying wonders to deceive. When a seer gives a revelation that contradicts the gospel and gives false peace to those living in sin, we have strong reason to believe it is not from the Holy Spirit but from the flesh or from a deceiving spirit, telling the world what it wants to hear.
What is the likelihood she is legitimate. We would say it is very unlikely. A legitimate messenger from God does not claim to see the Father's face in contradiction to Scripture, does not offer blanket assurance of Heaven apart from repentance and faith in Jesus Christ, and does not draw attention to her own spiritual sight. She would point people to Jesus, to the cross, to repentance, and to the Word.
We also notice your request speaks of God and the Bible and Christian, but does not mention the name of Jesus Christ, and we want to gently remind you that it is only through Jesus that we have access to God and assurance of Heaven. Jesus said to him, I am the way, the truth, and the life. No one comes to the Father, except through me John 14:6. 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 Acts 4:12. If that celebrity or anyone else truly belonged to Christ, it would be because they repented and put their faith in Jesus alone, not because they claimed the label Christian while loving the world. If we confess with our mouth that Jesus is Lord and believe in our heart that God raised him from the dead, we will be saved Romans 10:9.
So we encourage you not to let this trouble rob your peace, but to let it sharpen your discernment. Stay rooted in the Word daily, test every voice by Scripture, and pray for wisdom, for God gives wisdom liberally to those who ask. Do not feel you must decide the eternal destiny of this celebrity, for the Lord knows those who are His, but do warn others lovingly that claiming to be a Christian while living in open rebellion is a fearful deception.
We pray together for you now.
Father in Heaven, in the name of Jesus Christ Your Son, we come before Your throne of grace. We ask You to grant our friend discernment and peace and to guard their heart from confusion and false teaching. Help them to test the spirits and to love Your truth even when the world loves a lie. We pray for all those deceived by Hollywood Christianity and by false seers who speak smooth things, that You would open eyes to see the need for true repentance and faith in Jesus alone. We pray for the family and fans of the one who died, that they would not be given false comfort but would be drawn to seek You while You may be found. Expose what is false and let Your Word stand as the lamp to our feet. Keep us from familiar spirits and soothsaying and keep us close to Christ. We ask this in the mighty name of Jesus, our only hope and our only way to You, amen.
Prayer Focus: God, Thank You for loving me. Thank You for loving me, Jesus. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. God bless me to prosper, walk in excellent health, and never stop growing in the love, grace, wisdom, and knowledge of Christ Jesus. God bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. God, bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, Your righteousness, and to always respect and obey You. Bless me to know You, the way You want me to know You. So that I will trust You with my life and anyway that You move in my life. Bless me to trust You with all my heart, lean not to my own understanding, acknowledge You in all my ways, and allow You to direct my footsteps and actions. Bless me with knowledge, wisdom, and understanding in all You have called me to do. 
