Question: I don't see anything in Scripture that says the 12 Apostles were baptized. I see where St. Paul was baptized. But not the 12.
It's in there. Not everything in Scripture is explicit. Protestants, hold to a rule that everything must be explicit in Scripture. But we don't.
So, where does Scripture say that the Apostles were baptized. Probably many places, but here are the three most obvious ones, where we can make this inference.
First, Jesus said:
Mark 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Jesus doesn't hold the Apostles do different standards. Therefore, if they claim to believe, they must also have been baptized.
Second, Jesus also said:
There was a man of the Pharisees, named Nicodemus, a ruler of the Jews: The same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him. Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God. ...
We believe we are born again in Baptism and therefore, we believe that Jesus would have required the Apostles to be baptized, in order that they could be born again, before they could be His disciples.
And finally, Scripture also says:
John 13:4 He riseth from supper, and laid aside his garments; and took a towel, and girded himself. 5 After that he poureth water into a basin, and began to wash the disciples' feet, and to wipe them with the towel wherewith he was girded.
You probably recognize the foot washing episode at the Last Supper? Right?
6 Then cometh he to Simon Peter: and Peter saith unto him, Lord, dost thou wash my feet?
St. Peter balked at the idea that Jesus, the Son of God, would bend down to wash his feet.
7 Jesus answered and said unto him, What I do thou knowest not now; but thou shalt know hereafter.
Jesus tried to persuade him by saying that, although he didn't understand the meaning of the gesture, now, he would understand it, later.
8 Peter saith unto him, Thou shalt never wash my feet.
But St. Peter still objected. He didn't want to see his beloved Master doing such a humiliating task.
Jesus answered him, If I wash thee not, thou hast no part with me.
But Jesus said, "If I don't wash your feet, you'll have to leave my company."
9 Simon Peter saith unto him, Lord, not my feet only, but also my hands and my head.
To which St. Peter replied, "well, if washing is so important, then wash me from head to toe."
Pause for a moment. Here comes the part that addresses the question of whether the Apostles were baptized or not. Keep two things in mind.
1. Baptism means washing.
2. Jesus is washing the 12 Apostles' feet.
10 Jesus saith to him, He that is washed needeth not save to wash his feet, but is clean every whit: and ye are clean, but not all.
Did you get that?
He that is washed, means, "he that is baptized".
Needeth not to be washed save his feet , means, "does not need to be baptized again, but needs to repent, confess his sins and be reconciled to God."
and ye are clean, means that he has been washed of his sins because he has been baptized.
but not all. This is a reference to Judas Iscariot, who was baptized, but did not believe. Thus, bringing on himself the curse of Mark 16:16.
Therefore, then, in this verse, Jesus says that all the people whose feet He washed, were baptized (i.e. washed). And since it is only the Apostles who were baptized, Jesus has just revealed that the Apostles were baptized. He just doesn't come out and use the word, "baptized". He uses a different word, which means the same thing.
I hope that helps.