Much of today's modern evangelism and missions has as its focus and primary impetus the happiness of man rather than the holiness of God and His glory. There is an attempt to utilize God for man's happiness with everything existing for the happiness of man. With this view, heaven exists for man's happiness, Jesus Christ was incarnate and crucified for man's happiness, and the angels and all of creation are for the happiness of man. However, this is humanism, utilitarian religion, unChristian, and unbiblical. The happiness of man is a by-product of his holiness (which suits him for fellowship with God - "Follow peace with all men, and holiness, without which no man shall see the Lord" Hebrews 12:14) and holiness is the prime-product of the gospel ("Who gave Himself for us to redeem us from every lawless deed, and to purify for Himself a people for His own possession, zealous for good deeds" Titus 2:14).
A man-centered approach to ministry will always result in a toned-down God (He's really not so Holy and so far above us), a lifted-up man (he's really not so bad and so far below God), and a watered-down message void of true heaven sent power. And this will turn missions upside down with missions existing primarily for the benefit of man rather than the glory of God. The true call to missions is always who will go for God - not who will go for man. Isaiah, after seeing the holiness of God and His glory heard God say, "Whom shall I send, and who will go for us?" (Isaiah 6:8).
This right view of the holiness of God and His glory along with the wickedness of man against the backdrop of God's holiness ("Woe is me, for I am ruined! Because I am a man of unclean lips, and live among a people of unclean lips; for my eyes have seen the King, the Lord of hosts" Isaiah 6:5) will guard against the wrong motivation and focus of ministry (humanism and the happiness of man) and restore the correct impetus to missions (the holiness of God and His glory).
Here is a five minute excerpt from Paris Reidhead's Ten Shekels and a Shirt that powerfully explains the correct philosophy (theology) of missions.