Only God knows this person's heart, and whether or not he has truly committed his life to Jesus Christ. We must never forget Jesus' warning: "Do not judge, or you too will be judged" (Matthew 7:1).
At the same time, this man's actions are wrong, and they certainly contradict his claim to be a follower of Christ. A person who is constantly angry has never allowed the Holy Spirit to take control of his life; the Bible says, "The fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control" (Galatians 5:22-23). Nor has a person who dishonors God by his speech allowed the Holy Spirit to control his mind and his tongue.
Christians aren't perfect; we still have our old sin nature within us, and we still fall short of what God wants us to be. But no sincere believer ignores his or her sin, or acts like it isn't important. When we sin, we know we have offended God, and we want to confess it and seek His help for the future.
Don't let this person's bad example keep you from facing your own need of Christ and turning to Him for the forgiveness you need. Satan will try to persuade you otherwise but God loves you, and the most important decision you will ever make is your decision to open your heart to Christ's transforming power.