Theology and Science (Taylor & Francis / CTNS). Submit from the journal page, "Submit an article" button, which opens its ScholarOne site: https://www.tandfonline.com/journals/rtas20. Author instructions: https://www.ctns.org/research/journal/author-instructions. All submissions should be made online at the Theology and Science Manuscript Central site, with a 100-word abstract and roughly 5,000 to 8,000 words. It is hybrid open access, so if you choose not to publish open access in this journal, there is no APC.
Zygon: Journal of Religion and Science (Open Library of Humanities). Submit through the journal's own site: https://www.zygonjournal.org. Note the platform change: from July 14, 2023, the Wiley ScholarOne website can no longer be used for unsolicited submissions. Authors of unsolicited submissions should proceed to the following website: https://www.zygonjournal.org. Roughly 5,000 to 9,000 words, abstract under 200 words, Chicago author-date, double-anonymous peer review. It is diamond open access, no author charge.
The Islam-and-science venues.
Journal of Islamic Sciences (Center for Islamic Sciences). Submission guidance is on the Authors page: https://jis.cis-ca.org/authors.html. It is not an automated portal, so submission is by the instructions there. Strong topical fit, and confirm it is currently open before you invest the reformat.
American Journal of Islam and Society (IIIT). Submit via its OJS: https://www.ajis.org/index.php/ajiss/about/submissions, registering first at https://www.ajis.org/index.php/ajiss/user/register. Interdisciplinary, names philosophy and metaphysics in scope, double-blind, open access.
International Journal of Islamic Thought (UKM, Malaysia). Template and guidelines: https://www.ukm.my/ijit/guidelines/, fee page https://www.ukm.my/ijit/fees/, contact ijit@ukm.edu.my. Thematically this is the closest of all: the current issue runs Algorithmic Predestination and Divine Knowledge (`Ilm Allah): Causality, Human Agency, framing predictive systems as a "false qadar" against Ashʿari and Muʿtazili positions, which is your exact qadar-and-free-will register. It is Scopus and WoS-ESCI indexed and CC BY open access. One real caveat: it Requires IMRaD writing structure and uses APA, so a humanities essay would need structural reformatting to fit. Weigh the topical fit against that.
Two alternates.
International Journal for Philosophy of Religion (Springer). Submit from the journal page, "Submit manuscript" button: https://link.springer.com/journal/11153. Non-sectarian, represents no single institution or sectarian school, philosophical or religious, good if you ever recut it as philosophy of religion rather than confessional theology.
Religions (MDPI). Submit via the MDPI system: https://susy.mdpi.com/user/manuscripts/upload?journal=religions, with author instructions at https://www.mdpi.com/journal/religions/instructions. Broad and fast, but it carries a charge: the Article Processing Charge (APC) for publication in this open access journal is 1800 CHF.
If I were sequencing it: Theology and Science first, since it already publishes both your halves and costs nothing to submit, then Zygon. Send to the Islamic venues if you want the explicitly Islamic readership, with IJIT the best thematic match but the one that demands the most reformatting.