The Glorious Gospel

If a preacher tries to 'popularize' the Truth of the Gospel is that the same as preaching a false gospel? Is 'watering down' the Gospel 'antichrist'? What is the only 'sound doctrine'? How is the Word of God the only standard to uphold when preaching? Why is it so important to understand that the True Gospel is the Gospel of God? Can a man truly bless God when they contend with His Truth in Christ? How is it that some hear the Voice of Christ and others only hear a voice when the Gospel is preached?