Everything we have is a gift from God.
Regarding salvation, the Gift of salvation, which is addressing the work that Christ did for mankind, does not need to be received. It is given to us to use and one part of it is imposed upon. Even those that never believe will have been given this gift. It is stated in Rom 5:14, 18, II Cor 15:22, That Gift is being freed from the bondage to death and sin. Man had nothing to do with this gift.
Because of this gift of salvation of the world, God is also calling all men to repentance to be joined with Him. This is an offer to each individual to be united with God. He does not need to do this, but in not doing it would deny the very purpose of why He created us.
This is the Gift that one needs to receive or accept. We accept it be believing that Christ saved us from death and sin. But in believing, this union has obligations. It is not just a passive state, or benign concept. It requires work because that is why God created us, to be co-workers with Him. He created man to be a prophet, priest and king with God over this created order. That clearly imples a lot of work. Man does not just sit idely by and acquiece to what God might be doing.
God does not revoke any of his gifts. But the gift or offer of union with Him does have conditions attached. If man does not live up to his commitments, then man has broken the covenant. Man is the one responsible for his actions, not God. Whlich is why man will be judged in the last day. God does not give grace to swine to have it trampled underfoot. Which is why doing so is almost a guarantee that you cannot repent from such a direct, knowingly, conscious rejection of Christ once we have entered into a relationship with Him.
Why would God revoke anything, since He created us, then redeemed us, and desires that all men believe and come to the knowledge of Him, (be saved).