Psalm 111:9 (KJV) states, referring to God, "Reverend is his name." Some interpret this as saying the title "reverend" is to be used of God alone and vehemently oppose any human church leader being referred to as “reverend.” The original Hebrew word, though, is not referring to a title. It is declaring that God’s name is to be "revered, highly respected." The NIV, NAS, NKJV, and ESV all render the Hebrew word “holy and awesome” instead of the KJV’s rendering of “reverend.”
Whatever the case, if you are uncomfortable using the title "reverend" for a church leader, by all means, use some other title. In most churches/denominations, the title of “reverend” is given to a person who has undergone formal ministry training and has been examined by those in church leadership. This is commonly known as “ordination.” A “reverend” is a person who has been formally “ordained” into the ministry. First Timothy 5:17 states, "The elders who direct the affairs of the church well are worthy of double honor, especially those whose work is preaching and teaching." A godly man who exemplifies 1 Timothy 3:1-13 and sets a godly example in word and deed is worthy of being "respected." Whether or not the title of “reverend” should be used is a matter of personal conviction and preference.