In the first reading St. Paul asks us to live by the spirit, rather than by the flesh. In saying that he was speaking as one raised in the Greek world where the moral tone was set by the Philosophy of the Stoics. While the Jews in their ancient heritage thought of us humans as integrated persons brought to life the way Adam was: by receiving the breath of life from God, the Stoic Philosophy of the Greeks saw us humans as assembled of two warring parts: the flesh and the spirit. As modern Christians we are more comfortable with the holistic approach that calls for having both healthy bodies and healthy minds.
In the middle of today’s reading Paul switches to a different consideration of our spirits. The Greeks were fond of an Old Wife’s Tale that said when a child is conceived he receives something of his father; and even though he grows up without seeing that father, when he first meets him that bit of his father’s spirit that he received at his conception will cause him to recognize his true father, prompting him to call out “Abba, Father!”
By comparing a Christian’s baptism to his spiritual conception Paul says that in a baptized Christian ever afterwards the spirit he received at his conception will enable him to see God as his true father, causing him to call out, “Abba, Father.”