@Jim
In your OP, you wrote: "I don’t see any reason in any of that to think that baptism with physical water is a requirement for following Jesus, or that God has rules about when and how to do it."
My short response: Water baptism may be obligatory in order to become an accepted member of this or that group of Christians, but it is not an obligatory act when following Jesus.
My longer response: From Psalm 51 (minus the last two verses) [New American Standard Bible]:
1 Be gracious to me, O God, according to Your lovingkindness;
According to the greatness of Your compassion blot out my transgressions.
2 Wash me thoroughly from my iniquity
And cleanse me from my sin.
3 For I know my transgressions,
And my sin is ever before me.
4 Against You, You only, I have sinned
And done what is evil in Your sight,
So that You are justified when You speak
And blameless when You judge.
5 Behold, I was brought forth in iniquity,
And in sin my mother conceived me.
6 Behold, You desire truth in the innermost being,
And in the hidden part You will make me know wisdom.
7 Purify me with hyssop, and I shall be clean;
Wash me, and I shall be whiter than snow.
8 Make me to hear joy and gladness,
Let the bones which You have broken rejoice.
9 Hide Your face from my sins
And blot out all my iniquities.
10 Create in me a clean heart, O God,
And renew a steadfast spirit within me.
11 Do not cast me away from Your presence
And do not take Your Holy Spirit from me.
12 Restore to me the joy of Your salvation
And sustain me with a willing spirit.
13 Then I will teach transgressors Your ways,
And sinners will be converted to You.
14 Deliver me from bloodguiltiness, O God, the God of my salvation;
Then my tongue will joyfully sing of Your righteousness.
15 O Lord, open my lips,
That my mouth may declare Your praise.
16 For You do not delight in sacrifice, otherwise I would give it;
You are not pleased with burnt offering.
17 The sacrifices of God are a broken spirit;
A broken and a contrite heart, O God, You will not despise.
TRIVIA:
- Water Baptism -- John the Baptist. The nature and content of John's baptism:
- Mark 1: 4,5 "John came baptizing in the wilderness and preaching a baptism of repentance for the remission of sins. Then all the land of Judea, and those from Jerusalem, went out to him and were all baptized by him in the Jordan River, confessing their sins."
- Water Baptism -- Jesus and his disciples. Essentially the same baptism as John's, but it's different in the sense of Jesus being present, Jesus giving authority to his own disciples to baptize, and the fact that Jesus baptized more people than John.
- John 3: 22 "After these things Jesus and His disciples came into the land of Judea, and there He remained with them and baptized."
- John 3: 26 "And they came to John and said to him, 'Rabbi, He who was with you beyond the Jordan, to whom you have testified – behold, He is baptizing, and all are coming to Him!' "
- John 4: 1-3 Therefore, when the Lord knew that the Pharisees had heard that Jesus made and baptized more disciples than John (though Jesus Himself did not baptize, but His disciples), He left Judea and departed again to Galilee."
- Baptism of Suffering – Jesus (and the disciples).
- Luke 12: 49,50 [Jesus says:] "I came to send fire on the earth, and how I wish it were already kindled! But I have a baptism to be baptized with, and how distressed I am till it is accomplished!" (This "baptism" has been interpreted as being "submerged in a sea” of opposition, suffering and hatred)
- Matthew 20: 22,23 (also Mark 10: 38-40) "But Jesus answered and said, '“You do not know what you ask. Are you able to drink the cup that I am about to drink, and be baptized with the baptism that I am baptized with?' They said to Him, 'We are able.' So He said to them, 'You will indeed drink My cup, and be baptized with the baptism that I am baptized with; but to sit on My right hand and on My left is not Mine to give, but it is for those for whom it is prepared by My Father.' ”
- Water Baptism in the Name of Jesus AFTER Jesus' resurrection and prior to his ascension.
- Matthew 28:19 "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit."
- Mark 16:15,16 "And He said to them, 'Go into all the world and preach the gospel to every creature. He who believes and is baptized will be saved: but he who does not believe will be condemned.' ”
- Acts 2: 38 "Then Peter said to them, 'Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit.'"
- Acts 8:12 "But when they believed Philip as he preached the things concerning the kingdom of God and the name of Jesus Christ, both men and women were baptized.
- Acts 8: 35-38 "And the eunuch said, 'See, here is water. What hinders me from being baptized?' Then Philip said, 'If you believe with all your heart you may.' And he answered and said, 'I believe that Jesus Christ is the Son of God.' .... both Philip and the eunuch went down into the water, and he baptized him."
- NOTE: Pre-crucifixion and post-crucifixion baptisms are similar in that both are in water and both are preceded by a call to repent and be baptized for the remission of sins.
- Baptism in (or with) the Holy Spirit.
- When John was asked about his baptism, he always mentioned the one who was coming after him, (the Messiah), who would baptize with the Holy Spirit and fire
- Matthew 3:11 / Luke 3:16 "I indeed baptize you with water unto repentance, but He who is coming after me is mightier than I.....He will baptize you with the Holy Spirit and fire."
- Mark 1:8 "I indeed baptize you with water, but He will baptize you with the Holy Spirit."
- Jesus himself told the disciples just before he ascended.
- Acts 1:5,8 For John truly baptized with water, but you shall be baptized with the Holy Spirit not many days from now.....But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth."
- Day of Pentecost. Acts 2: 1-4 "When the day of Pentecost had fully come, they were all with one accord in one place. And suddenly there came a sound from heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting. Then there appeared to them divided tongues, as of fire, and one sat upon each of them. And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit gave them utterance.