Romans 3
What advantage then has the Jew, or what is the profit of circumcision? 2 Much in every way! Chiefly because to them were committed the [a]oracles of God. 3 For what if some did not believe? Will their unbelief make the faithfulness of God without effect? 4 Certainly not! Indeed, let God be [b]true but every man a liar. As it is written:

“That You may be justified in Your words,
And may overcome when You are judged.”

The Jews are still God’s chosen people. Even though some people do not believe it does not change that God is true, and God is just.

Charles Spurgeon once said:
“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.”

Our job is to show Christ. That is why circumcision does not matter if you still choose to disobey God. The outwardly act must be followed by a lifestyle reflecting Christ. If we were to all reflect Christ, more people would come to the saving knowledge of our Lord Jesus. We would also live amazing lives where we would see the hand of God in our every day as we believe for amazing signs and wonders.