Acts 2:38 certainly is the word of God and so is Acts 3:19; 5:31; 10:43; 11:17,18; 15:8,9; 16:31; 26:18 etc.. We need to properly harmonize scripture with scripture before reaching our conclusion on doctrine and not isolate pet verses, build doctrine on them and ignore the rest or try to force the rest to "conform" to a biased interpretation of a pet verse.
The scriptures you referenced, with the exception of Acts 16:31-33 (ref to belief and water baptism), line up with the command given by Peter on the Day of Pentecost; repent, be baptized everyone of you in the name of Jesus Christ for the remission of sin and you shall receive the gift of the Holy Ghost.
Acts 3:19
19
Repent ye therefore, and
be converted, that your sins may be blotted out, when the
times of refreshing shall come from the presence of the Lord;
Acts 5:31-32
31 Him hath God exalted with his right hand to be a Prince and a Saviour, for
to give repentance to Israel, and
forgiveness of sins.
32 And we are his witnesses of these things; and so is also the
Holy Ghost, whom God hath given to them that OBEY him.
Acts 10:43-44
43 To him give all the prophets witness, that
through his name whosoever believeth in him shall receive remission of sins. (water baptism)
44 While Peter yet spake these words, the
Holy Ghost fell on all them which heard the word.
Acts 11:17-18
17
Forasmuch then as God gave them the like gift as he did unto us, who believed on the Lord Jesus Christ;
what was I, that I could withstand God?
(MY COMMENT - He did not withstand God. He water baptized them-Acts 10:47
Can any man forbid water, that these should not be baptized, which have received the Holy Ghost as well as we?)
18 When they heard these things, they held their peace, and glorified God, saying, Then hath
God also to the Gentiles granted repentance unto life.
Acts 15:7-11 (No OT Circumcision Necessary)
7 And when there had been much disputing, Peter rose up, and said unto them, Men and brethren, ye know how that a good while ago God made choice among us, that
the Gentiles by my mouth should hear the word of the gospel, and believe.
8
And God, which knoweth the hearts, bare them witness, giving them the Holy Ghost,
even as he did unto us;
9 And put no difference between us and them,
purifying their hearts by faith.
10 Now therefore why tempt ye God, to put a yoke upon the neck of the disciples, which neither our fathers nor we were able to bear?
11 But we believe that
through the grace of the Lord Jesus Christ we shall be saved, even as they.
Acts 16:31-33 (Only belief and water baptism reference)
And they said,
Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house.
32 And
they spake unto him the word of the Lord, and to all that were in his house.
33 And he took them the same hour of the night, and washed their stripes;
and was baptized, he and all his, straightway. (At midnight-not much of a public display)
Acts 26:18-20
18 To
open their eyes, and to turn them from darkness to light, and from the power of Satan unto God,
that they MAY receive forgiveness of sins, and inheritance among them which are
sanctified by faith that is in me.
19 Whereupon, O king Agrippa, I was not disobedient unto the heavenly vision:
20 But shewed first unto them of Damascus, and at Jerusalem, and throughout all the coasts of Judaea, and then to the
Gentiles, that they should repent and turn to God, and do works meet for repentance.