As-salam alaykum brother Daniel,
To be become a 'believer' from a Quran's perspective (in general), one would need to have submitted (i.e. become a Muslim first).
049:014
The desert Arabs say, "We believe! (Arabic: Amana)" Say, "Do not say you believe (Arabic: tu'minu); but only say, 'We have submitted our wills to God (Arabic: Asalamna),' as belief (Arabic: l-imanu) has not yet entered your hearts. But if you obey God and His Messenger, He will not deprive you anything of your deeds: for God is Oft-Forgiving, Most Merciful
This does not mean that Muslims of old (that predated the Quran) were any less believers as they believed all that had been revealed to them. We are referring specifically to the term ‘believers’ from the point from the prophetic ministry and post the Quran’s revelation.
Therefore, a 'believer' from a Quran's perspective is one who also recognises the Quran as truth and God's word (i.e. belief in all the revealed Books).
For example, the Quran recognises that there were 'believers' from the People of the Book at the time of the prophetic ministry who believed in what was revealed to them and what was revealed to the Prophet.
003.199
"And there are, certainly, among the People of the Book (Arabic: Ahli-l-kitabi), those who believe in God, in the revelation to you, and in the revelation to them, bowing in humility to God: They will not sell the Signs of God for a miserable gain! For them is a reward with their Lord, and God is swift in account"
This is clearly a two-tier system where plurality is recognised. The people who believe in the final revelation are still being referred to as the People of the Book (Ahli-l-kitabi)
017.107-108
"Say: Believe in it or believe not; surely those who are given the knowledge before it fall down on their faces in prostration when it is recited to them. And they say: Glory be to our Lord! most surely the promise of our Lord was to be fulfilled"
005.083
"And when they listen to the revelation received by the Messenger, you will see their eyes overflowing with tears, for they recognise the truth: they pray: "Our Lord! we believe; write us down among the witnesses"
028.052-53
“Those to whom We sent the Book before this, they do believe in this (revelation). And when it is recited to them, they say: "We believe in it, for it is the Truth from our Lord: indeed we have been Muslims from before this"”
Here the difference between the Quranic usage of the term 'Muslim' and 'Believers' is clear. A Muslim is anyone who submits to the will of God as a monotheist. Believers (Arabic: Amanu) are specifically those that have belief in the final scripture of God (i.e. the Quran), as truth from Him.
From my humble perspective (and only God knows best), someone like yourself would arguably be a 'believer' from a Quran's perspective (28:52-53) from the People of the Book.
I hope that clarifies, God willing,
Joseph