Some people are like this, I'm afraid; no matter what the problem is, they blame God -- even if they are responsible for what went wrong. Jesus faced the same problem; some people lashed out at Him because He showed compassion to those in need: "Why are you angry at me for healing the whole man on the Sabbath?" (John 7:23).
But must they always be this way? Not necessarily -- for God's love is stronger than their anger, and He can wash it away and fill them with His love. One example was the apostle Paul, who in his younger days hated those who followed Jesus, and even sought to kill them. But on the road to Damascus (where he was going to find and imprison those who were believers), Jesus Christ appeared to him -- and his life was changed. Later, he wrote, "Even though I was once a blasphemer and a persecutor and a violent man, I was shown mercy because I acted in ignorance and unbelief" (1 Timothy 1:13).
Pray for your friend, that God will convict him of his sin and turn his heart toward Christ. In addition, ask God to help you be an example to him of Christ's peace, hope and love. And as you have opportunity, ask him what makes him so angry.
Don't neglect your own spiritual growth, either. We may compare ourselves to someone who's violently opposed to God, and we end up satisfied with our spiritual state. Don't let this happen to you, but put Christ first in your life every day.