“Calvinism stresses that saving faith is a gift of God.”
All Christians agree that salvation is the gift of God (Eph 2:8), but not all agree that God gives saving faith to some, while hating others and not allowing them to believe.
No, not all Christians believe salvation is a gift from God.
Many believe that one must earn it in some way.
If one does believe that salvation is God's gift, then inevitably comes the question of why that gift is not given to all. And this is where the debate arises. It is a valid debate if one does believe that salvation is a gift.
However, the truth remains that is one is gifted by God to receive salvation, assurance for the saints is the end-result. A remarkable blessing to walk in day by day, to be sure, one of which many true saints are unaware since condemnation is a persistent enemy while we are here on earth.