Notes from Adam Clarke’s Commentary on the Bible on Acts 13:48:
“As many as were ordained to eternal life believed—This text has been most pitifully misunderstood. Many suppose that it simply means that those in that assembly who were fore-ordained; or predestinated by God’s decree, to eternal life, believed under the influence of that decree. Now, we should be careful to examine what a word means, before we attempt to fix its meaning. Whatever τεταγμενοι may mean, which is the word we translate ordained, it is neither προτεταγμενοι nor προορισμενοι which the apostle uses, but simply τεταγμενοι, which includes no idea of pre-ordination or pre-destination of any kind. And if it even did, it would be rather hazardous to say that all those who believed at this time were such as actually persevered unto the end, and were saved unto eternal life.
But, leaving all these precarious matters, what does the word τεταγμενος mean? The verb ταττω or τασσω signifies to place, set, order, appoint, dispose; hence it has been considered here as implying the disposition or readiness of mind of several persons in the congregation, such as the religious proselytes mentioned Acts 13:43, who possessed the reverse of the disposition of those Jews who spake against those things, contradicting and blaspheming, Acts 13:45.
Though the word in this place has been variously translated, yet, of all the meanings ever put on it, none agrees worse with its nature and known signification than that which represents it as intending those who were predestinated to eternal life: this is no meaning of the term, and should never be applied to it.
Let us, without prejudice, consider the scope of the place: the Jews contradicted and blasphemed; the religious proselytes heard attentively, and received the word of life: the one party were utterly indisposed, through their own stubbornness, to receive the Gospel; the others, destitute of prejudice and prepossession, were glad to hear that, in the order of God, the Gentiles were included in the covenant of salvation through Christ Jesus; they, therefore, in this good state and order of mind, believed.
Those who seek for the plain meaning of the word will find it here: those who wish to make out a sense, not from the Greek word, its use among the best Greek writers, and the obvious sense of the evangelist, but from their own creed, may continue to puzzle themselves and others; kindle their own fire, compass themselves with sparks, and walk in the light of their own fire, and of the sparks which they have kindled; and, in consequence, lie down in sorrow, having bidden adieu to the true meaning of a passage so very simple, taken in its connection, that one must wonder how it ever came to be misunderstood and misapplied.”