I think that the identity of the last three of the horsemen is generally acknowledged as the sword, famine and pestilence - the three agents of God’s wrath mentioned many times in OT prophecy. The is much conflict as to the identity of the first, white, horse. Some say it’s Jesus, some say its the anti-christ, and some, like here, say it’s Jesus’ Gospel being preached to the world.
The white horse I think symbolizes Antichrist and it’s attending man centered philosophies(or the various social type “isms”), such as progressive socialism and hedonistic Utopianism, that seek to peal men away from God to serve a man centered state....which in turn leads to war, famine and pestilence. When people are stripped of their basic moral moorings, societies eventually become tyrannical, then implode in their inability to negotiate the fiscal, legal, and security demands placed upon that society. External enemies may view such societies as ripe for the picking...such as how Islamic Jihadis may view western nations at this time. The white horse symbolizes the attempt to forcibly build a “new world government” by force and by the use of a syncretized civil religion with Satan at the back of it all.
Civil wars result, famine and disease become rampant as persons of competence who could ameliorate the conditions are killed off by the political agencies of the dying regimes, by disease or strife, or they have gone into hiding and are missing. The 4 horsemen depict a dark vision of the future of humans being brought to the very end of ourselves and our vain attempts to make ourselves into “gods”. Only by Christ intervening will save what ever life is left upon the Earth at that time.