Some clarification would be nice, and the point of comparison is not that Jesus is a νήπιος, but that God's people were prior to coming into relationship with Jesus. νήπιος often has implications of foolishness, and it's hard to see that applied to Jesus. Similarly δοῦλος -- the son and heir is not a δοῦλος per se, but shares certain elements of being under that type of authority until he comes into his inheritance. In a parallel fashion, God's people are slaves (to what?) until they turn to Christ and become heirs and sons. BTW, in Latin, the freeborn children of the paterfamilias (head of the household) were called liberi (literally "free") where as a slave child was called a verna. So at least the Romans made this distinction quite sharply, and Paul must have been aware of that, living as a Roman citizen in the Empire.
Clarification is good and BDAG does a good job. Rather than "silly" the νήπιοι are the child-like, innocent ones, unspoiled by learning, with whom God is pleased Mt 11:25; Lk 10:21
Liddell Scott does give a metaphorical usage from Homer for silly. But BDAG does not because it is not "our literature."
Don't you think that we should inform our Christian view from what Jesus said?
5112 νήπιος
• νήπιος, ία, ιον (Hom.+; ins, pap, LXX, En; TestSol 18:25 L; Test12Patr; JosAs 12:7 cod. A; ApcEsdr 5:3 p. 29, 27 Tdf.; SibOr; Philo, Joseph.; Ar. 10, 7; Tat. 30, 1; Ath., R. 17 p. 68, 31) in Gk. lit. ν.
gener. refers to beings ranging from fetal status to puberty. In our lit.
1. a very young child, infant, child
a. lit. (ViDa 1 [p. 76, 13 Sch.]; Jos., Ant. 6, 262; Ar. [Milne 76, 40] ἐὰν δὲ νήπιον ἐξέλθῃ; Orig., C. Cels. 3, 48, 26 ἀμαθὴς καὶ ἀνόητος καὶ ἀπαίδευτος καὶ ν.; Theoph. Ant. 2, 25 [p. 160, 6] Ἀδὰμ ἔτη ν. ἦν) ὡς ν. βρέφη like veritable babes Hs 9, 29, 1. Usu. subst. child sing. 1 Cor 13:11abcd (for ν. opp. ἀνήρ Orig., C. Cels. 3, 59, 23); τὰ τοῦ ν. childish ways vs. 11e. Pl. τὰ ν. (sc. βρέφη) Hm 2:1; s 9, 29, 1. The gen. pl. of the neut. is prob. to be understood Mt
21:16 (Ps 8:3; s. JGeorgacas, ClPl 76, ’58, 155).
b. fig.; the transition to the fig. sense is found Hb 5:13 where the νήπιος, who is fed w. the milk of elementary teaching, is contrasted w. the τέλειος=‘mature person’, who can take the solid food of the main teachings (s. also 1 Cor 3:1f). In this connection the ν. is one who views
spiritual things fr. the standpoint of a child. W. this can be contrasted
α. the state of the more advanced Christian, to which the ν. may aspire (Ps 118:130; Philo, Migr. Abr. 46; Iren. 4, 38, 1 [Harv. II 293, 2]) ITr 5:1. ἵνα μηκέτι ὦμεν νήπιοι Eph 4:14. A Judean as διδάσκαλος νηπίων Ro 2:20. νήπιος ἐν Χριστῷ immature Christian 1 Cor 3:1 (cp. ὡς νηπίοις, ὁ ἄρτος ὁ τέλειος τοῦ πατρὸς, γάλα ἡμῖν ἑαυτὸν παρέσχεν [on the accent s. Schwyzer I 391] ‘seeing that we were but infants, the perfect bread [=the Son of God] of the Father gave himself as milk to us’ Iren. 4, 38, 1 [Harv. II 293, 8]; JWeiss, Paulin. Probleme: Die Formel ἐν Χριστῷ Ἰησοῦ, StKr 69, 1896, 1-33). Harnack, Die Terminologie d. Wiedergeburt: TU XLII 3, 1918, 97ff.
β. The contrast can also be w. the ideas expressed by σοφός, συνετός, and then the
νήπιοι are the child-like, innocent ones, unspoiled by learning, with whom God is pleased Mt 11:25; Lk 10:21 (GKilpatrick, JTS 48, ’47, 63f; WGrundmann, NTS 5, ’58/’59, 188-205; SLégasse, Jésus et l’enfant [synopt.], ’69). Cp. also 1 Cl 57:7 (Pr 1:32).
2. one who is not yet of legal age, minor, not yet of age, legal t.t. (UPZ 20, 22 [II BC] ἔτι νηπίας οὔσας ὁ πατὴρ ἀπέδωκεν εἰς σύστασιν Πτολεμαίῳ) ἐφ᾿ ὅσον χρόνον ὁ
κληρονόμος ν. ἐστιν as long as the heir is a minor
Gal 4:1. Fig. vs. 3.—In 1 Th 2:7 νήπιοι is accepted by Lachmann and W-H., as well as by interpreters fr. Origen to Wohlenberg, Frame, et al.; Goodsp., Probs. 177f. S. also SFowl, NTS 36, ’90, 469-73: the metaphors of infant and nurse are complementary. Others, incl. Tdf., HermvSoden, BWeiss, Bornemann, vDobschütz, Dibelius, Steinmann, prefer ἤπιοι (v.l.), and regard the ν of νήπιοι as the result of dittography fr. the preceding word ἐγενήθημεν (s. the entry ἤπιος). MLacroix, Ηπιος/Νηπιος: Mélanges Desrousseaux ’37, 260-72.; B. 92.—New Docs 1, 116; 4, 40. DELG. M-M. TW. Sv.