We come to "saving faith" in Christ because God changes/regenerates us, giving us the needed desire and the ability to do so. So while we are the ones doing the "believing", it's only possible for us to believe because God made it possible. Saving faith is a "gift" that God gives to His Elect (Ephesians 2:8; cf Acts 13:48).
You are misinterpreting Eph. 2:8
I can look up genders and dust off my Greek New Testament, but here is what Barnes and Robertson have to say and they do an honest job as far as I can tell:
And that not of yourselves - That is,
salvation does not proceed from yourselves. The word rendered "that" - ͂ touto - is in the neuter gender, and the word "faith" - ́ pistis - is in the feminine. The word "that," therefore, does not refer particularly to faith, as being the gift of God, but to "the salvation by grace" of which he had been speaking. This is the interpretation of the passage which is the most obvious, and which is now generally conceded to be the true one; see Bloomfield. Many critics, however, as Doddridge, Beza, Piscator, and Chrysostom, maintain that the word "that" ( ͂ touto ) refers to "faith" ( ́ pistis ); and Doddridge maintains that such a use is common in the New Testament. As a matter of grammar this opinion is certainly doubtful, if not untenable; but as a matter of theology it is a question of very little importance.
Robertson, on the topic of pronouns, wrote:
9.
Gender and Number of outos. ... In general, like other adjectives,
outos agrees with its substantive in gender and number, whether predicate or attributive. ... In
Eph. 2:8, ..., there is no reference to
pisteos in
touto, but rather to the idea of salvation in the clause before. (A. T. Robertson,
A Grammar of the New Testament, p.704)
Robertson, on the topic of particles, wrote:
(ii)
Kai. ...
The Mere Connective ('And') ...
kai tauta (frequent in ancient Greek). See in particular
Eph. 2:8, kai touto ouk ex umon, where touto refers to the whole conception, not to chariti. (A. T. Robertson,
A Grammar of the New Testament, pp. 1181-1182)
Robertson, on the topic of prepositions, wrote:
(d)
dia ...
3. 'Passing Between' or 'Through.' The idea of interval between leads naturally to that of passing between two objects or parts of objects. 'Through' is thus not the original meaning of dia, but is a very common one. ... The agent may also be expressed by dia. This function was also performed in the ancient Greek, through, when means or instrument was meant, the instrumental case was commonly employed. dia is thus used with inanimate and animate objects. Here, of course, the agent is conceived as coming in between the non-attainmnet and the attainment of the object in view. ... Abstract ideas are frequently so expressed, as sesosmenoi dia pisteos (
Eph. 2:8), ... (A. T. Robertson,
A Grammar of the New Testament, pp. 580-582)
"Gift" and "faith," are both nouns and would not need to agree. However, agreement in gender is necessary between a pronoun and its antecedent. The demonstrative pronoun will change its gender to match the previous noun (or other substantive) to which it refers.
This verse tells us that the antecedent for "This" is also the "gift of God." But the "gift" cannot be "faith" because there is no agreement in gender between "faith" and the demonstrative pronoun, "touto" (This).
You can look up lots of Greek scholars work and let me know if you find any one disagreeing with this, because I have not seen alternatives among scholars.
Please look carefully: More then just the grammar you have to explore all the context: Eph. 2: 8For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— 9not by works, so that no one can boast.
The gift is taught to not be gotten by works, so if the “gift” was “faith” how would someone even consider getting “faith” by working for it? That is not a plausible concept that would need to be expressed and especially taught against. We are taught in scripture other places that you can not earn or work for salvation and it is a gift. But where else is it taught to not “work” to earn “faith”? We understand “faith” as trusting in God for our salvation and not working to earn salvation.
As far as Acts 13: 48 goes:
God has ordained or foreordained from the beginning of time that all those that believed would be given eternal life. It is not that the “ordaining to eternal life” that forced some gentiles to believe, but they believed which were also foreordained to eternal lives as a result of that believe. Eternal life and believe go together, but we know you have to believe to have eternal life and you are not “gifted” with eternal life without believing.
You might look at alternative interpretations of Acts 13:48 and go through the 8 times the Greek word “hosoi ēsan tetagmenoi” is used in scripture to consider other alternatives.