How many times in history the very "good and perfect gift" that only comes from God, do men, to whom those gifts are given, destroy by their own sluggishness, pusillanimity, neglect, worldly interests?!
The ten virgins in the famous parable were given the same gifts, all from the Above, but five of them were wise and worked on them, increased them and made thus themselves worthy of salvation; on the contrary the other five, the fools, were lazy and negligent, so did not increase divine gifts and were thus disqualified from the Kingdom (Matthew 25:1-13). The same is expressed in a parable about the master distributing talents (Matthew 25:14-30): all those talents signify the divine gifts, which can be only "good and perfect", yet the servants utilize those gifts differently, achieving different degrees of perfection, while one of the servants does not utilize it at all and buries it, that is to say, destroys it. Which is to say that "good and perfect" divine gifts can avail for nothing unless we freely co-act with those gifts. Our free co-action is not already a part of this gift, but our free initiative.
Thus, to avoid the extreme Augustinian and Jan Calvinian dangerous pitfall and in a heedless and euphoric celebration of divine goodness abolish human free initiative and arrive then necessarily to a double predestination monstrosity, we must answer to your question clearly negatively and say that NO, our free initiative to co-operate with divine grace and gifts (and, in fact, divine gift is a more everyday name for theological notion "divine uncreated operation") the divine grace by itself will not save us. Very similarly, when Ronaldinho is given no lesser talent, but even more, than Messi, yet by lack of his co-operation with this talent (women, night-clubs etc.) does not achieve as much as Messi, then this is a clear proof that not only talent does things, but our initiative as well, for how then a greater talent - Ronaldinho became eventually lesser footballer than Messi in the history of football?
Actually, the Lord Himself says that His gift can be "taken away" from an unworthy owner, and He not only does not but, due to His infinite love, cannot even take His gift from us unless we ourselves lose it through our sluggishness, self-conceit, lack of devotion etc.(Matthew 13:12). Now, if unworthiness is totally on the part of a man, then keeping oneself in worthiness is also totally on the part of a man for only thus obtains the salvific synergy (θεοῦ γὰρ ἔσμεν συνεργοί /1 Cor. 3:9/). Yes, if we become lukewarm in devotion and the Lord will therefore decide to spit us out of his mouth, it is not His, but our fault and responsibility, as keeping ourselves thankfully in devotion is likewise (cf. Rev.3:16). As st Athanasius duly says: "Ascetic cultivation of virtue is more valuable than miracle-working, for miracle is totally God's deed, while ascetic cultivation of virtue a joint deed of God's grace and man".
Had everything been from God, we necessarily go to Calvinism, which is a nightmare.