The modern doctrine of the universal fatherhood of God which is being celebrated as “the essence of Christianity,” really belongs at best only to that vague natural religion which forms the presupposition which the Christian preacher can use when the gospel is to be proclaimed; and when it is regarded as a reassuring, all-sufficient thing, it comes into direct opposition to the New Testament. The gospel itself refers to something entirely different; the really distinctive New Testament teaching about the fatherhood of God concerns only those who have been brought into the household of faith.
There is nothing narrow about such teaching; for the door of the household of faith is open wide to all. That door is the “new and living way” which Jesus opened by His blood. And if we really love our fellow men, we shall not go about the world, with the liberal preacher, trying to make men satisfied with the coldness of a vague natural religion. But by the preaching of the gospel we shall invite them into the warmth and joy of the house of God. Christianity offers men all that is offered by the modern liberal teaching about the universal fatherhood of God; but it is Christianity only because it offers also infinitely more.
J. Gresham Machen, Christianity and Liberalism (Kindle Edition)