Only God knows this person’s heart, and whether or not her faith in Jesus Christ is real; God alone is her judge. The Bible, however, warns us against “faith” that isn’t really faith at all, but is only a shallow pretense or an outward show. The Bible says, “Such a person is double-minded and unstable in all they do” (James 1:8).
But the Bible also clearly tells us that gossiping is wrong and shouldn’t be part of any sincere believer’s life. One reason is because its purpose is wrong. You don’t gossip about someone to build them up; you do it to belittle them or cast doubt on their character. How many lives have been destroyed by gossip? The Bible wisely says, “Without wood a fire goes out; without gossip a quarrel dies down” (Proverbs 26:20).
But gossip is also wrong in God’s eyes because (as you suspect) it’s often based on lies. Even if it’s based on facts, the temptation to shade the truth is almost overwhelming. The Bible says, “Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up” (Ephesians 4:29).
Don’t let this person’s bad example keep you from Christ. Instead, open your heart and life to Him, and let Him remake you into the person God created you to be. Then pray for this person, and urge her to face her own need for Christ’s forgiveness and love.