Romans 12:1 has a very interesting phrase which is translated in a several different ways. Here are some translations of it:
NRSV, NASB, ESV: Spiritual worship.
NIV: True and proper worship.
KJV, NET: Reasonable service.
Each of these translations means something very different from the others. “Spiritual worship” and “true and proper worship” tend to focus on your connection with God. “Reasonable service” focus on your actions in reaction to the force of Paul’s theology. So, which translation is it? Let’s work through one word at a time.
The first word (reasonable/spiritual) could mean spiritual. This meaning is derived from 1 Peter 2:2 where the context is considering spiritual things (cf. 1 Pet. 2:5) and a passage in Philo that links it to spiritual things (Schreiner).
It could mean rational. This meaning is derived from the actual use of the word in secular Greek language. In general, it can mean logical, speaking or possessed of reason (Liddell and Scott; spiritual is not listed as an option).
I prefer the second option for several reasons. The first is that it follows the normal pattern of speech and is devoid of interpretational bias. Also, just because the substitution of the word spiritual works in these contexts does not mean that it is the right one. One could easily substitute desirable or pleasing in these contexts. These words make sense and they could be argued from the context of the passage, but it does not follow that these are legitimate possibilities. Certainly, λογικὴν is related to the spiritual life, but that fact does not mean they are synonyms (Schreiner). Further, it follows a deep theological and rational discussion which drive a rational conclusion. And after this statement, Paul continues to focus on the rational mind in verse two. This does not mean it is any less a spiritual or doxological conclusion (cf. Rm. 11:36), but all this theology produces a reasonable argument for Christians to serve God. Indeed, the only reasonable thing to do after understanding this theology is to serve God. Thus, rational seems to be the best rendering here.
The second word is worship or service. It could mean worship. This rendering is derived from the religious use of the term within the Scriptures (Ex. Ex. 12:25-26, 13:5, Jn. 16:2). For a specific example of how worship was done, in the Old Testament, the Transjordan tribes performed worship to the Lord with sacrifices (Jos. 22:27). In the New Testament, the author of Hebrews described the rituals of the Old Covenant as worship (Heb. 9:6).
It could mean service. The common use of this term outside of the scriptures is “the state of a hired labourer” (Liddell & Scott). Inside the Greek version of the Old Testament, this word translates the term ‘bodah which means work or service. While the Hebrew term can mean non-cultic service, the Old Testament reserves this word for religious service. The contexts of these religious practices are the rites of the Passover (Ex. 12:25-26, 13:5), the memorial sacrifices of the Transjordan tribes (Jos. 22:27), the persecution of Christians (Jn. 16:2), and the rituals of the Law performed in the temple (Rm. 9:4, Heb. 9:1, 6). The verb form the word also translates various words for labor, service and plowing. However, the Old Testament only uses it in religious contexts like the noun form. Thus, with the emphasis on service, labor and actions and with its clear religious context, it seems best to translate the word as service or labor for God. As for the English word worship, it does not convey the meaning of labor for God very well and it is a rather ambiguous term in English. It can mean anything from good feelings about God, to songs, hymns and preaching, to a meeting at a given time and place. While these ideas are not wrong, they just are not intended by the word in Romans 12:1 and so this translation can be misleading.