Adam Clarke on John 5:44

How can ye believe, which receive honor, etc. - The grand obstacle to the salvation of the scribes and Pharisees was their pride, vanity, and self-love. They lived on each other's praise. If they had acknowledged Christ as the only teacher, they must have given up the good opinion of the multitude; and they chose rather to lose their souls than to forfeit their reputation among men! This is the ruin of millions. They would be religious, if religion and worldly honor were connected; but as the kingdom of Christ is not of this world, and their hearts and souls are wedded to the earth, they will not accept the salvation which is offered to them on these terms - Deny thyself: take up thy cross, and follow Me. It is no wonder that we never find persons making any progress in religion who mix with the world, and in any respect regulate their conduct by its anti-Christian customs, maxims, and fashions.

From God only? - Or, from the only God - Παρα του μονου Θεου. Two of the ancient Slavonic versions read, From the only begotten Son of God.