When you say // but it is God who gives a person the ability to receive and to be saved./// what do you mean? this could be affecting how your reading the text maybe .
Thanks for asking. The Bible says: "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. " This means that God takes the initiative and gives a person that he wants saved to hear his gospel. God draws people to Jesus by giving them the spiritual ability to hear unto salvation.
Thankfully, this takes the knowledge of who is saved away from a person or a bunch of people who say that they know or have the ability to decide instead of God. Thank goodness it is God who knows the heart and who is truly Love.