For what if some did not believe? shall their unbelief make the faith of God without effect? …let God be true, but every man a liar… – Romans 3:3,4

Will God fail to keep His promise to anyone who believes on Him? Because some do not believe, will God’s promise therefore fail to be kept to those who do believe? I invite you to come and try. When two of John’s disciples enquired of Jesus where He dwelt, He said to them, “Come and see.” If any person here will try Christ, as I tried Him when yet a youth, as miserable as I could be, and ready to die with despair, if they shall feel in believing such joy as I felt, if they shall experience such a change of character as passed over me when I believed in Christ, they would not tolerate a doubt. What they have known, and felt, and tasted, and handled of the good Word of God, will prove to them that, if some believe not, yet God abideth faithful, He will never deny Himself.

Will God be unfaithful to His Son if some do not believe? I have heard sometimes a fear expressed that Christ will lose those for whom He dies. I thank God that I have no fear about that. “He shall see the travail of His soul and shall be satisfied.” I never come to you, and, in forma pauperis, ask you to accept Christ, begging and praying you to take Christ, because otherwise He will be a loser by you. It is you who must beg of Him. He giveth grace as a king bestows his favours; nay more, He lovingly condescends to entreat you to come to Him. Suppose that you wickedly say, “We will not have Christ to reign over us.” If you think that you will rob Him of honour, and bring disgrace upon Him by your rejection, you make a great mistake. If you will not have Him, others will. If you who are so wise will not have Christ, there are plenty whom you reckon to be fools who will take Him to be their “wisdom, and righteousness, and sanctification, and redemption.” This word shall yet become true. “The kingdoms of this world are become the kingdoms of our Lord and of His Christ, and He shall reign for ever and ever.” ~ C.H. Spurgeon

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