Why? To "worship God and wage war against the enemy."
From the Breath of Worship site:
At times, during the course of a service, the Holy Spirit may instruct Mark to minister on the drums or symphonic gong. During these moments, people’s lives have been deeply touched and often experience a sudden manifestation of the presence of God. A prolific speaker, Mark’s high energy, down-to-earth teaching style utilizes both his speaking ability and custom digitized sound effects, thus using sound teaching to declare the Word of the Lord. A moment with God, it lingers for a lifetime.
Whether preaching from behind the pulpit or playing the drums, one of the most appreciated aspects of Pastor Mark’s ministry is the use of the prophetic gifts. God is using his fresh approach prophetically as a catalyst to WAKE UP America from the shadow of indifference that has swept across this nation.
The first time Mark played drums in a Church was in 1978.Since that time God has used his drumming, teachings with signs & wonders to touch the lives of hundreds of thousands of people all over the world. God uses Dr. Marks, high energy teaching style. And his unique abilities to declare the Word of God. At times the Holy Spirit may instruct him to minister on the drums or play the symphonic gong. During these moments, people often experience a sudden manifestation of the Glory of God. It is an experience people never forget and lives are deeply touched.
Mark plays for an audience of ONE – “The Creator of the Universe”! Everybody else gets the overflow and all the Glory goes to God!
You may notice that the immense drum set features only one bass drum. Says RevM, "I only use one bass drum on my main set because there is only “ONE GOD” and only One way to get to Heaven and that is through Jesus Christ." Makes perfect sense.
Visit the site for more, including an FAQ, and a breakdown of his gear.