“…for I know whom I have believed, and am persuaded that He is able to keep that which I have committed unto Him against that day.” – 2 Timothy 1:12

I could never be content without unquestioning certainty as to my soul’s salvation. Do you think that is more than a man ought to wish for? Are any of you at ease while you are afraid that you have a mortal disease working within you? Oh, no! You want to know, from a qualified physician, the truth about your case. And if it were whispered in your ear, at this moment, that your house was being broken into or was on fire, would you sit still here, and not trouble yourself as to whether the report were true or not? Would you not want to go at once, and see for yourself. If you knew that you bought an estate, some time ago, but you have since heard that the title to it is a very uncertain one, in fact, that, in all probability, you will lose all you have paid for it, would you not say, “I ought to have taken care to be certain about the title, and I would not have bought the estate if I had not felt that the deeds relating to it were all right”. Well, then, if you desire certainty about your bodily health, and about the safety of your house, and about the validity of your title-deeds, can you afford to go without certainty as to your soul’s affairs? No, you cannot; therefore, rest not till you have it. If you have various questions about your spiritual condition, boldly face those questions, and answer them; but never let any questions about your eternal welfare be such that you dare not face them, and do not wish to search out the answers to them. Pry to the very bottom of them; and, better still, ask the Lord to search you, and know your heart, to try you, and know your thoughts, and to lead you in the way everlasting; and be not content till you can truthfully say, “I know whom I have believed, and am persuaded that He is able to keep that which I have committed unto Him.”~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/2667.cfm