If the Lord is not calling someone to Himself, then they are not going to believe that He exists, at least not in the manner that glorifies Him. They may accept the possibility that there is some form of a “higher power,” someone or something that is beiger than us, that has more control over the situation, if you please, but they will in no way honor Him as such.
There are, as far as I am able to determine, only three possible reasons for this, perhaps four. They have been blinded by Satan, “And these are they by the way side, where the word is sown; but when they have heard, Satan cometh immediately, and taketh away the word that was sown in their hearts.” (Mark 4:15) Some are self-blinded, pride has a covering over their heart, or the Lord has not called them, which may or may not be tied to the fourth possibility, that they are vessels fitted to destruction. (Romans 9:22)
As best as the finite mind can comprehend, the first is a puzzle, to say the least, it infers that there is at least a modicum of desire to search for this “higher power” they presume exists, this God that is being spoken to them by the Word, but that in some way, Satan has the power to place within these individuals a diversion, a deception, another thought that takes away from their hearing the desire to see it as truth. It is, in the best comparison that I can give it at this time, such as he offered to Eve, a choice that causes debate within the mind of a secondary option that was heretofore unbeknownst to the individual. In this scenario, the fault still lies within the hearer, for we are created free will beings, capable of making logical, deductive choices based on all the relevant information.
The second, that of a “self-blindness,” I can see no other reason for but pride, of not wanting to be kicked off of the throne of our lives, our notion that we are the masters of our own destiny, and as such, any one or anything that places a stumbling block in our path is not only despised but hated. Christ is the stumbling block, (1 Cor. 1:23) for He is the pinnacle of power. These individuals would no more worship Him than they would give continued fealty to someone over them without some form of personal gain from that individual, life surrounds them.
This, I believe, is the majority of people, they are the ones that may call upon Him in the direst of straights, but only then, and only if their very lives, or the way that they believe it should be, is in peril. They can be many times the pretenders, but more than likely those are found in our third group, those whom the Lord has not called. “That seeing they may see, and not perceive; and hearing they may hear, and not understand; lest at any time they should be converted, and their sins should be forgiven them.” (Mark 4:12)
I know what it sounds like, and the soul that strives to be pleasing in the eyes of God can have much difficulty with this verse and others like it. It can sound as if free will has been taken away, for many will listen when the Word is given, but will not hear, and if they did hear, it would be only because God is calling them to Christ, for “No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.” (John 6:44) And so, what we comprehend is that the Lord is hindering them from hearing, for His own reasons, for His own glory.
And that is why I mentioned that this third analogy is closely tied to the fourth, “What if God, willing to shew his wrath, and to make his power known, endured with much longsuffering the vessels of wrath fitted to destruction.” (Romans 9:22) I no longer struggle with this verse, “God forbid: yea, let God be true, but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged.” (Romans 3:4) He is Sovereign, and as such He alone is the only One that truly understands our free will and His grace towards that free will, we cannot.
For me personally, contemplating the questions that only the Lord God can answer is the way that I draw closer to Him, and I can only do that if He bids me to come to Him. Those of us who have been saved by His grace are, in all actuality, the only group that has been blessed with the ability and the desire to ponder these unanswerable questions, and we would be wise to do so on a regular basis.