Ephesians 2:4-9 But God, who is rich in mercy, for his great love wherewith he loved us, Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved) and hath raised us up together, and made us sit together in heavenly places in Christ Jesus: That in the ages to come he might shew the exceeding riches of his grace in his kindness toward us through Christ Jesus. For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast.
What did God give?
A gift is not a reward for good behavior. When you work for something you earn a wage. You can not earn a gift. When we give gifts or presents and we tell children (and adults) that we are giving them a gift because they have behaved well or done a good job, then we are not using the word gift as God uses it in His Word. We must not read into the Word the idea of working to receive gifts. A gift is given freely without regard to the "goodness" of the recipient.
A gift is also not something you exchange. When God gave us the gift of holy spirit the Word says we were "dead in sins." We were not in any position to exchange with God. What did we have that was worth what God gave? Nothing! Even if we had "been good" and tried to walk a godly walk, we were dead. Exchanging gifts is bartering. It is swapping. It is trading. You know, you gave me such and such so I have to try to give you something of equal value. Once again, God gave because of mercy, love, grace, and kindness; not because of what we gave Him.
A gift is not something you take back if the person offends you. We tell children: "If you don't keep behaving properly I will take back that which I gave you for being good." A gift has no strings. God's Word tells us that when God gives a gift he does not take it back:
Romans 11:20 For the gifts and calling of God are without repentance.
Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning. James 1:17
See also: GWT-235 "Do You Believe in Gifts?"