Only God knows the heart of any person who claims to be a Christian, and it isn't our place to judge them or decide whether or not they actually are a believer. This is what Jesus meant when He told His disciples, "Do not judge, or you too will be judged" (Matthew 7:1).
However, any Christian who has a joyless attitude and is always looking on the dark side of things is missing much of what it means to be a Christian. It's true, of course, that we live in a very troubled world, and Christians especially should be burdened for a world that has lost its way and abandoned God's will. As Jesus prayed in the Garden of Gethsemane shortly before His arrest and death, we read that He was "in anguish ... and his sweat was like drops of blood falling to the ground" (Luke 22:44).
But Christians also should be filled with joy and peace—not because everything around them is perfect, but because they know Christ is in control. The Bible says, "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control" (Galatians 5:22-23).
Don't forsake Christ because of the imperfections of one of His followers. Instead, face your own need of Him and open your heart and life to His transforming power today.