John 1.19

'And this is the record of John, when the Jews sent priests and Levites and priests from Jerusalem to ask him, Who art thou?'

It is one of the peculiarities of the Gospels that the Jewish establishment  and their supporters are referred to as being 'the Jews'. Clearly John the Baptist was a Jew, as was John the Evangelist who wrote this particular Gospel. As indeed was Jesus of Nazareth, his mother Mary, his friends Martha and Mary, their brother Lazarus, and all the apostles too.
In the land of Israel, in those days, there were two hierarchical power structures, the military power and the ideological, priestly power. The military power was in the hands of the Romans and their collaborators, such as the Herods. The religious power remained with the Jews. So when the Evangelist states 'the Jews priests and Levites' he was referring to the indigenous religious elite, in the same way that we might say 'the Romans invaded Britain,' whereas most probably the majority of Romans had little to do with it.
The Roman government was not interested in John the Baptist because he did not appear to threaten them. On the other hand John was an increasingly powerful source of religious authority. They would want to assimilate or destroy.
Modern day Jews, like Reformed Christians, do not have priests and so both groups are a threat to the principle of earthly authority, and so both groups are often persecuted.
The 'Jews' sent the priests and the Levites to quiz John the Baptist because they felt threatened.

John 1.18

'No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared him.'

No man has ever seen God, except God the Son, the Word, our Lord Jesus Christ.
Our Lord 'hath declared him.'
In his words, his teachings, his miracles, above all in his life and death Our Lord has revealed God.
Jesus Christ has revealed the Truth of God.
There is no need for further revelation. L.Ron Hubbard, Joseph Smith, and any others who add to Scripture are false prophets.
Jesus Christ has revealed God's nature, his love divine, the sacrificial love, the giving, serving love that is the creative force of the universe, the Word of Creation, the Light of Life, our destiny to sing the praises of Divine Love for all eternity.

John 1.17

'For the law was given by Moses, but grace and truth came Jesus Christ.'

This verse sort of sums things up. The law was given by Moses, the law of God, the Law of Love. This great gift lifted mankind out of the rut of superstition and fear, and servitude to kings and idols.
Though following the Law was no guarantee of an easy life, it was clear that blessings flowed to those who who honoured God, kept the Sabbath, refrained from greed, slander and so on. The Jews of today will tell you as much.
With the Law of God there is no need for a king. God's Law trumps all others, much to the annoyance of bureaucrats and tyrants through the the ages.
Those who obey the Law have no need to fear the random anger of a king or nature god, or idol created from Man's imagination.
But the Law also condemns us in the eyes of the one perfect Living God. Our sin is only wiped clean by the sacrifice of Our Lord, the Lamb of God. This is the grace divine, wonderous and kind, of our God. And through the grace of our Lord jesus Christ, the fulness of God's great love, and his purpose is revealed to us . This is his Truth, his purpose, his wisdom, his perfection, his holiness.

John 1.16

'And of his fulness have we all received and grace for grace.'

Jesus Christ, the Son of God, who was before John the Baptist, who came after John the Baptist, who is preferred before every man and woman, has given of the fulness to those who believe.
It is a remarkable thought that we have received of the fulness of God. Only our stubborn pride forbids us from enjoying such fulness.
Yet God's love is overflowing. His love is free, unmerited, boundless. Such is the nature of grace, such is the nature of God.
For God's love is giving, selfless and sacrificial. It is the stuff of life. Each time we bargain and manipulate our fellows we die a little, we deny a little of the Divine Love.
It is in giving that we live, giving in the abundance we receive from God, even if our abundance appears to us a 'mite'  like that of a widow.
In giving, without expectation of earthly reward, we are truly alive.

John 1.15

'John bare witness of him, and cried, saying, This was he of whom I spake, He that cometh after me is preferred before me: for he was before.'

John the Baptist was clearly a well known local prophet whilst Jesus was still unknown. When the time of his ministry came Jesus was proclaimed by the Baptist.
What is so important about the baptism that John gave his followers? Before we can receive forgiveness we need to repent. Before we can see our Redeemer we need to acknowledge our servitude.
Often I find with non-Christans that behind the scepticism about the literal truth of the Bible is an unwillingness to recognize their servitude, or the fact that being on balance a 'good' person is not enough.
Before we can know our Lord Jesus Christ as our saviour we need to repent of our sin  -  that is our sin, not our specific sins. We are not called to wrack our brains in egotistical contemplation before we are allowed into God's presence, but we must acknowledge that we are sinners, we must regret and repent our sin, we must mourn our sin.
John the Baptist was washing away the sins of his followers in preparation for the coming of the Lamb of God and his Kingdom of Heaven, when a people free from sin and superstition, receiving God's unending love, would receive grace for grace, and live fully eternally, in God's presence.

John 1.14

'And the Word was made flesh, and dwelt amongst us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.'

Wow! The Incarnate God is proclaimed. God takes on a human life and lives amongst us. John the Evangelist  says that 'we' beheld his glory. The 'we' are the sons of God, given the eyesight to behold the glory of the Word made flesh.
The Word, our Lord Jesus Christ, is the only begotten son of the Father. Jesus Christ is of the essence of the Father.
In other words he is equal to the Father  -  under his authority but equal  -  like a human child is equal to its parents yet are under their authority.
He is begotten, not created - a very important thing to remember, the only begotten Son of God.
For a few brief years Jesus 'dwelt' among us . He lived, suffered, loved as one of us. he never succumbed to sin, yet he knew temptation. He could not sin, for God cannot sin. It is God's nature to be full of Truth.
And Grace too - God's irrevocable love for us, his children, unmerited by us, freely bestowed by the Lord - a love unconditional and eternal.
Full of Grace and Truth  - one of my favourite phrases in the whole Bible. It sums up our Lord in a nutshell.

John 1.13

'Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.'

The sons of God, those who believed 'on his name', those who 'received him', those to whom he gave 'power to become the sons of God,' were born of woman, of course, but in their true eternal life they were born of God.
Many wishful thinkers like to believe that God resides in all of us, that all of us are chosen by God. Then there are others who like who like to believe that they are responsible for their belief, that somehow, for all their human fraility, they have found God, made a decision, accepted the Almighty. but they are no more active in their birth in Christ than a new born baby is active in her emergence from her mother's womb.
The sons of God are not are not born 'of blood' or 'of the will of the flesh', nor 'of the will of the man', but solely, wholly completely of the will of God.
The heathen enjoys the Common Grace of the beauties of and the joys of this world, of love and laughter and prosperity, as well as the fruits of Common Sin, but the heathen lives absorbed in himself, above him only sky, and when his hour comes, he will suffer eternal death.
But the sons of God can praise the Lord in this world, and bask in his Eternal Truth for ever more, the sons of God, the Elect, born of the will of God.