uhm isn't rejecting that considered as not knowing?
13 For ye have heard of my conversation in time past in the Jews' religion, how that beyond measure I persecuted the church of God, and wasted it: 14 And profited in the Jews' religion above many my equals in mine own nation, being more exceedingly zealous of the traditions of my fathers. 15 But when it pleased God, who separated me from my mother's womb, and called me by his grace,
but when he was called he heard it
there really is a time for everything
and it can't be forced
Every soul that receives the gospel and is born again by the Spirit of God (the Holy Spirit) was chosen to be in Him from before the foundation of the world, but yes, there is a moment in time when we believe Him, receive Him, and are made alive (spiritually) which is according to His election and His grace. I also believe that there are those that are chosen from the womb for specific purposes. My mom was a devout Roman Catholic, and like many Catholic women had desired that one of her children would become a priest or nun and spend life serving God. things didn't quite work out the way she planned. I was the last of 3 boys and none of us kept any sort of strong relationship with the RCC. However my mom did dedicate my life to Him (as the last of her children) though she didn't tell me this until well into my adulthood. While I had a real love for the Jesus of the gospels and a desire to be like Him, my scripture reading from an early age made me less than enthusiastic about a church where I was roughly handled and smacked around by people professing to be servants of God. I also became concerned about the apparent disregard of commandments and instructions to the church that I regularly observed among the "clergy." The result was that I stopped attending masses immediately after being " confirmed" in the faith and was granted that desire by my father (in opposition to mom's wishes.) I spent the best part of the first 39 years of my life, studying a mixture of science, religion, philosophy, and occultism because of a strong desire to know the truth. I experienced many unusual things, some of which proved the reality of the spiritual nature of the world to me, but it was not until I was ministered to (for some years) by two faithful born again Christians, coworkers at my place of employment, that patiently answered my questions and demonstrated a certain sanctification in their lives, that I was convinced that the scripture was really inspired of God and wholly true. I finally understood and believed the gospel at the age of 39 and it most certainly changed the direction of my life. All these things were sovereignly ordered by God according to His will and not my own.
I can't really imagine someone "hearing" God's call through the work of His Spirit and rejecting it. Yet, Jesus taught parables in the face of the Pharisees that pointed to them knowing exactly who He is, but still rejecting Him and killing Him in order to keep their power and authority. If anyone truly walks away from God and never returns to Him, it's highly unlikely that they ever knew Him in the first place. To receive His Spirit is to gain immediate and direct access to the Father. Knowing His character, His mercy and His justice, His love and His grace, it is inconceivable to me that anyone could just walk away from Him (permanently), but there's a huge difference between being "religious" and knowing Him. Even knowing about Him, through study of the scripture, is no guarantee of knowing Him experientially by His Spirit and so people may be self deceived in their presumption. This one thing I know to be true, because Jesus said so:
If you then, being evil, know how to give good gifts to your children, how much more will your heavenly Father give the Holy Spirit to those who ask Him!” Luke 11:13