The Synoptic Gospels tell us God was pleased with Jesus at his baptism. Therefore, any Synoptic claim about what pleases God may serve as implicit testimony about Jesus' life in Nazareth. For example:
If we repeat the assumption from post #1, that God's reward implies God's pleasure, then we may invert at least the following portions of Matthew's 6th chapter as historical reconstructions: When Jesus lived in Nazareth, it was customary for him to give to the poor, but he did it secretly. Often times Jesus would go into a room, close the door, and pray to his Father in secret. And sometimes Jesus would fast, but he kept his face washed and put oil on his head so that nobody could tell, except for the Father. In Nazareth, the Father saw Jesus do these things, probably for many years, and the Father was pleased with his Son.
Now, let's consider this argument.
The third point is of course repeated from post #1 and the earlier points are phrased very similarly in the passage. We may note once again that Matthew contrasts Jesus here with the Pharisees and characterizes this larger section of teaching as coming from one who spoke with authority <exousia>.
Incidently, this is the first time Matthew uses this word and four of its other eight uses come soon after this (7:29 => 8:9, 9:6, 9:8, 10:1). However we nuance and build our understanding of power/authority, I will simply suggest this much. The word means someone had the right to do something and/or the ability to do something. Matthew is saying Jesus had the right and/or the ability to teach these things. So if the crowds (and Matthew) believed Jesus was able to teach these things, is there any chance they believed Jesus was unable to do them? I think not.
Given these complimentary principles of power and sincerity in his teaching, we can probably justify inverting all of Matthew 5-7 as a valid reconstruction of Jesus' personal life. However, to date those behaviors to before his baptism, according to our arguments so far, we would also need to characterize the entire Sermon on the Mount as one complete teaching on how to please God. That can probably be done very easily, and may have been done before, but I'm not prepared to build and present that argument myself at the moment.
(Unless: if the SOTM is a condensed rendering of Jesus' Halakah, then it primarly addresses how to obey God's commandments, and doing what God commands is one third of our definition for pleasing Him.)
Just to be clear, I am in fact suggesting Matthew did intend the entire Sermon on the Mount not only as instructions for his readers but also as a reflection of Jesus' own disciplines. But the real problem for our purpose here is that after we justify that position (and date it pre-baptism), some details will be more challenging to invert and reconstruct from than others. We'll go through these in time, but for now, in this series, we'll take baby steps.
For all of these reasons, for now, let's keep things simple and stick with the principle at top. We are looking for behaviors and attitudes specifically offered, according to Matthew, as ones that God likes, that God wants, or that God commands. We have also added things that God "rewards".
It's very important to go slow, take our time, and be very careful we do not assume things. We should work very hard to sense out the boundaries between proving what are Matthew's direct implications and what might only be the sloppy, eager insertions our own preferred inferrences. However, if the argument at top is valid, we now have at least three personal habits/behaviors for Jesus in Nazareth. We have giving, prayer, and fasting, all done in secret and focused on the Father - that's not a bad start at all. We hereby claim these details (and possibly much more to come) as early biographical data purposely embedded in Matthew's testimony through direct implication.
I don't know about you, but I hear the Lord's "silent years" growing slightly louder.
To be continued...