Q. Why was God pleased with Jesus at his baptism? What had Jesus done at that point? Jesus had only been baptized, he had not started his ministry, but the heavens opened and God said, “This is my Son, whom I love; with him I am well pleased.”
I don’t think we should completely rule out the possibility that God the Father was saying that He was pleased with who Jesus had become to that point in his earthly life. Luke tells us that in Jesus’ youth and young adulthood, he “grew in wisdom and in stature and in favor with God and all the people.” So the Father could have been expressing His pleasure in Jesus’ godly character and spiritual maturity; Jesus had prepared well for the ministry he was just about to begin.
However, it’s important to realize that the language of being “pleased with” someone is actually the language of choice or selection in the Greek of the New Testament and the Septuagint (a Greek translation of the Old Testament that was widely used in the time of Jesus and the apostles). For example, there’s actually an extra psalm in the Septuagint. It’s considered Psalm 151 and it’s attributed to David, although its authorship is actually uncertain. But in it, the character of David describes how he became king. He says that the Lord’s messenger (that is, Samuel) “took me from my father’s sheep and anointed me with his anointing oil.” He adds, “My brothers were handsome and tall, but the Lord was not pleased with them.” This doesn’t mean that that the Lord didn’t like them. Rather, David is saying, “The Lord didn’t choose them instead of me.”
And so we should understand that when the Father says He is “well pleased” with Jesus at his baptism, He means in the same way, “This is the one I have chosen to be my Messiah.” As Gottlob Schrenk writes in The Theological Dictionary of the New Testament, “What is meant is God’s decree of election, namely, the election of the Son, which includes his mission and His appointment to the kingly office of Messiah.”
We find confirmation of this understanding later in the gospel of Matthew when the Father’s declaration at Jesus’ baptism is echoed in a quotation from the book of Isaiah:
Here is my servant, whom I have chosen,
the one I love, in whom I delight;
I will put my Spirit on him,
and he will proclaim justice to the nations.
Here the idea of being delighted in (i.e. having someone pleased with you) is used in exact parallel with the idea of being “chosen.” We also see again that the use of this phrase is accompanied by the gift of the Spirit for mission, just as in the case of Jesus’ baptism.
So while the Father was no doubt pleased by the way Jesus had matured into godly character in preparation for his ministry, the phrase “with him I am well pleased” actually indicates how God has chosen Jesus to be the Messiah.