James 1:5-Continually Ask God for Wisdom

Greek (SBLGNT): Εἰ δέ τις ὑμῶν λείπεται σοφίας, αἰτείτω παρὰ τοῦ διδόντος θεοῦ πᾶσιν ἁπλῶς καὶ μὴ ὀνειδίζοντος, καὶ δοθήσεται αὐτῷ·

When working with the Greek text, start with the postpositive conjunctive particle δέ: the particle either could be resumptive ("Now") or adversative ("But") or conjunctive ("And") or just be left untranslated.

A.T. Robertson (Word Pictures in the NT) explains that Εἰ δέ τις ὑμῶν λείπεται σοφίας is a first class conditional which is assumed to be factual (arguendo) since λείπεται is the present passive indicative third person singular of λειπω. See James 1:4.

A number of commentators understand σοφίας in this case to be wisdom in the face of trials (James 1:2-4), not just wisdom in general.

F.J.A. Hort states that James' use of λείπομαι with the genitive to mean "be wanting in" is rare. Additionally, James couples the verb with ὑμῶν and σοφίας, genitive case forms. A more recent James commentary in the Hermeneia series makes a similar point: the letter contains an infinitive in 2:15 and the participle at James 1:4 along with a prepositional phrase.  On the other hand, James 1:5 could be a genitive of separation. see Martin Dibelius and Heinrich Greeven, James (Hermeneia Series), page 77.

Another thing going on grammatically is that the genitive form in these cases serves as the direct object of λειπω. See Chris Vlachos, James.

αἰτείτω, a third person singular present verb form, could be iterative and it is imperative  (i.e., "let him keep on asking").

παρὰ τοῦ διδόντος θεοῦ πᾶσιν-Vlachos observes that the preposition denotes source and identifies the point from which the petition is granted. He offers these remarks:

Διδόντος is gen. sg. masc. of the pres. act. ptc. of δίδωμι, “give” (most EVV). The ptc. functions (1) adjectivally in the attrib. position as the modifier of θεός and (2) verbally with πᾶσιν as its indir. obj. and with the adv. ἁπλῶς as a modifier (for the attrib. ptc., see T 151-52; on the adjectival and verbal nature of ptcs., see R 1100-1101). A more natural word-order would have been παρὰ τοῦ θεοῦ τοῦ πᾶσιν ἁπλῶς διδόντος (see Mayor 39).

The way that James structures this part of his letter allows him to emphasize Jehovah God's generous nature (τοῦ διδόντος θεοῦ); Vlachos reckons that the participial διδόντος might be iterative but then he suggests it's likely gnomic instead because this usage could be more fitting within the speech context.

The dative πᾶσιν indicates God's range of generosity, and ἁπλῶς stresses the wholehearted aspect of God's giving nature (Vlachos): the adverb could mean "generously" or "wholeheartedly," singly (compare James 1:17).

καὶ μὴ ὀνειδίζοντος, καὶ δοθήσεται αὐτῷ-God gives without reproaching or disparaging the petitioner: he will never insult lovers of God for approaching him. The syntax again makes Jehovah's character salient, bringing it to the fore. James concludes by guaranteeing that the one who asks continually in faith will have whatever he requests, with the proviso that petitions be in harmony with God's will. See James 4:1-4.