John 3:12

If I have told you people ¹  about earthly things and you don’t believe, how will you believe if I tell you about heavenly things? ² 

I have spoken to you of earthly things and you do not believe; how then will you believe if I speak of heavenly things?

"If I told you earthly things and you do not believe, how will you believe if I tell you heavenly things?

But if you don’t even believe me when I tell you about things that happen here on earth, how can you possibly believe if I tell you what is going on in heaven?

If I tell you things that are plain as the hand before your face and you don't believe me, what use is there in telling you of things you can't see, the things of God?

If you have no belief when my words are about the things of earth, how will you have belief if my words are about the things of heaven?

If I have told you about earthly things and you do not believe, how can you believe if I tell you about heavenly things?

"If I have told you earthly things and you do not believe, how will you believe if I tell you heavenly things?

If I have told you people ¹  about earthly things and you don’t believe, how will you believe if I tell you about heavenly things? ² 

¹ tn The word “people” is not in the Greek text, but is supplied to indicate that the verb is second person plural (referring to more than Nicodemus alone).

² sn Obviously earthly things and heavenly things are in contrast, but what is the contrast? What are earthly things which Jesus has just spoken to Nicodemus? And through him to others – this is not the first instance of the plural pronoun, see v. 7, you must all. Since Nicodemus began with a plural (we know, v. 2) Jesus continues it, and through Nicodemus addresses a broader audience. It makes most sense to take this as a reference to the things Jesus has just said (and the things he is about to say, vv. 13-15). If this is the case (and it seems the most natural explanation) then earthly things are not necessarily strictly physical things, but are so called because they take place on earth, in contrast to things like v. 16, which take place in heaven. Some have added the suggestion that the things are called earthly because physical analogies (birth, wind, water) are used to describe them. This is possible, but it seems more probable that Jesus calls these things earthly because they happen on earth (even though they are spiritual things). In the context, taking earthly things as referring to the words Jesus has just spoken fits with the fact that Nicodemus did not believe. And he would not after hearing heavenly things either, unless he first believed in the earthly things – which included the necessity of a regenerating work from above, by the Holy Spirit.