Scripture says that ...
Jesus was NOT going around being "fully God" and able to do everything himself.
Even though Jesus, the man, had God * within him,
He still was a man and needed a lot of help from the Father and the Holy Spirit.
* It's my understanding that he had the Second Person of the Triune God within Him.
Luke 4:18
The Spirit of the LORD is upon Me, because He has anointed Me to preach the gospel to the poor;
He has sent Me to heal the brokenhearted, to proclaim liberty to the captives (of Satan)
and recovery of sight to the blind, to set at liberty those who are oppressed (by demons)
Luke 5:17
Now it happened on a certain day, as He (Jesus) was teaching,
that there were Pharisees and teachers of the law sitting by,
who had come out of every town of Galilee, Judea, and Jerusalem.
And the power of the Lord was present to heal them (the multitudes).
Hebrews 10:38
... how God anointed Jesus of Nazareth with the Holy Spirit and with power,
who went about doing good and healing all who were oppressed by the devil,
for God was with Him.
It is also my understanding that Jesus was NOT "fully man"
because since he was "without sin", he did not have man's sin nature.
There is one problem.
In ancient times tribal membership was inherited through the father's blood line. So a child born to a Jewish father and a Gentile mother would belong to the father's tribe, but would not be considered Jewish unless s/he converted at adulthood. In the same way the child of a Gentile father and a Jewish mother would be Jewish, but would have no tribal membership.
It is only recently that the Jews track tribal membership through the mother because they at least know who the mother is.
Ergo, if Joseph was not Jesus' biological father, Jesus would not have belonged to the tribe of Judah, which is one of the requirements of the Messiah.
If you are concerned about the cursed line of Jeconiah, here are a few notes:
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Reportedly, the kings of Judah did such evil that God cursed the line of Jeconiah in Jer 22:24-30, stating that no person of the seed of Jeconiah will ever sit upon the throne of David, or rule any more in Judah. Traditionally Christianity claims that since Jeconiah was cursed, the promised Messiah could not come from this male seed which was cursed. It is argued that this necessitates the virginal conception of Jesus. But, the curse against Jeconiah's male line was revoked. As Jeremiah clearly stated one could always reform his ways and actions and obey the voice of God. Then God would relent concerning the disaster that He had pronounced against one. [cf. Jeremiah 26.12-19]
How do we know that God relented concerning the curse He pronounced against Jeconiah ben Jehoiakim? In Haggai we read the following regarding Jeconiah's grandson, "I (YHVH) will take you, Zorobabel son of Salathiel, My servant", declares YHVH, "and I will make you like the signet ring for I have chosen you" declares YHVH of Armies. [2.23] The revocation of the curse by pulling off Jeconiah as "a signet ring on My right hand" is seen in making Jeconiah's grandson, Zorobabel, His "signet ring". The fact that YHVH *did* choose Zorobabel as His "servant" and that Jesus did come through Jeconiah's seed through Zorobabel (according to Matthew's genealogy) is further proof that God later cancelled the curse against Jeconiah's offspring.
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The only issue is that the Greek text of Matthew lends to the idea that Joseph wasn't the biological father. However, that is a textual corruption as the original reading is more likely to be what can be found in the Old Latin and Old Syriac translations of Matthew, where the text clearly indicate that Joseph was the biological father.
So we have a choice. If we want to hang onto the virginal conception idea, we don't have a Messiah.
... or we don't have the trinity.