I have met so many fakers ( "The haters of the Lord would pretend submission to HIM" Psalm 81:15 Spirit Life Bible ) in the church & have learned the only true way to tell if one is a Christian or not is to test the spirits, watch their walk, have they suffered for their faith or have they shown their love and devotion to the Lord with their tithes, offerings and service of evangelism to the Lord faithfully for at least five years without compromise. Then I would trust their confessions as being Christian. Just because they speak HIS statutes off their lips doesn't make them a Christian.
Unless you know that it is a new conversion that is a completely different scenario. Don't forget about the Rulers of God's people Israel who backslid into a wicked state namely Jezebel and Ahab. Or about Eli and his wicked sons, or Judas! The bible warns us that Satan will appear as an angel of light. And we are in the end times and the bible says that if it were possible even the very elect of God would be deceived. That is exactly how they would be deceived too is by one pretending that they are a saint when they are really Satan himself clothed as light or a Wolf in sheep's clothing so to speak.
My best friend was the most well respected, honored, prized possession of God that I have ever met. She even said that if she were the devil the first place she would go would be to church. And the devil himself quoted scriptures to Jesus so I am not surprised that some of Satan's people know the bible better than most preachers.
If you are a true Christian then in this day and age you should be really easy to spot. The bible tells how we are to know if one is a Christian or not is if they will have love one for the other. If they have love one for another they will not be back biting sheep stabbing another in the back with their tongue or using witchcraft against them. They will not lie about them or slander them steal from them if they love them.
And new Christians are so pure and clean and it doesn't matter what they were doing before they got saved. If they found the Lord they are cleaner than most who have gone to church for decades even if they just came out of a sexual immoral relation, a new age cult or even worse yet no religion at all. It doesn't matter if they are a new Christian they are saved if you think so or not!!!