For what if some did not believe? Will their unbelief make the faithfulness of God without effect? Certainly not! Indeed, let God be true but every man a liar. – Romans 3:3,4

Some will say, “If So-and-so, and So-and-so do not believe the gospel, then religion is a failure.” We have read of a great many things being failures nowadays. A little time ago, it was a question whether marriage was not a failure. I suppose that, by-and-by, eating our dinners will be a failure, breathing will be a failure, everything will be a failure. But now the gospel is said to be a failure. Why? Because certain gentlemen of professed culture and supposed knowledge do not believe it.

Man has gone from one form of philosophy to another, and every time that he has altered his philosophy, he has only made a slight variation in the same things. Philosophy is like a kaleidoscope. The philosopher turns it round and exclaims that he has a new view of things. So he has; but all that he sees is a few bits of glass, which alter their form at every turn of the toy. If any of you shall live fifty years, you will see that the philosophy to today will be a football of contempt for the philosophy of that period. They will speak, amidst roars of laughter, of evolution; and the day will come, when there will not be a child but will look upon it as being the most foolish notion that ever crossed the human mind. I am not a prophet, nor the son of a prophet; but I know what has befallen many of the grand discoveries of the great philosophers of the past; and I expect that the same thing will happen again. I have to say, with Paul, “What if some did not believe?” It is no new thing; for there have always been some who have rejected the revelation of God. What then? You and I had better go on believing, and testing for ourselves, and proving the faithfulness of God, and living upon Christ our Lord, even though we see another set of doubters, and another, and yet another ad infinitum. The gospel is no failure, as many of us know. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/2255.cfm