Serve Only Him

Then Samuel spoke to the whole house of Israel, saying,
“If you are returning to the Yehowah with all your hearts,
then put away the foreign gods and the Ashtoreths from among you,
and direct your hearts to the Yehowah and serve Him only;
and He will deliver you from the hand of the Philistines.”
So the children of Israel put away the Baals and the Ashtoreths
and served the Yehowah only. (1 Samuel 7:3–4)

The prophets and the apostles served only the Yehowah.
We also must serve only the Yehowah,
because those who oppose the Yehowah will be shattered.

Those who oppose the Yehowah will be broken to pieces.
The Yehowah will thunder against them from heaven.
The Yehowah will judge the ends of the earth; He will give strength to His king
and exalt the horn of His anointed. (1 Samuel 2:10)

Serve the Yehowah with fear,
and rejoice with trembling.
Kiss the Son, lest He be angry and you perish in the way,
for His wrath may quickly be kindled.
Blessed are all those who put their trust in the Yehowah. (Psalm 2:11–12)

Not believing that the One who came as a child is the Everlasting Father is to oppose the Yehowah.

For unto us a Child is born, unto us a Son is given;
and the government will be upon His shoulder.
And His name will be called Wonderful Counselor, Mighty God,
Everlasting Father, Prince of Peace.
(Isaiah 9:6)

The idea of God the Son existing from the beginning is a creation of the Catholic Church.
There is no such god.
If one does not abandon that god, one will perish.
The gospel is this: the Yehowah God who became the Son came in flesh
and blood and abolished death. Hallelujah!