Yes, water baptism is an appeal to God from a good conscience. If you don't make the appeal you probably won't get answer.
Your statement about apostolic teaching reveals much. Because it is the apostolic preaching that connects water baptism with salvation.
67 And his father Zacharias was filled with the Holy Ghost, and prophesied, saying,
68 Blessed be the Lord God of Israel; for he hath visited and redeemed his people,
69 And hath raised up an horn of salvation for us in the house of his servant David;
70 As he spake by the mouth of his holy prophets, which have been since the world began:
71 That we should be saved from our enemies, and from the hand of all that hate us;
72 To perform the mercy promised to our fathers, and to remember his holy covenant;
73 The oath which he sware to our father Abraham,
74 That he would grant unto us, that we being delivered out of the hand of our enemies might serve him without fear,
75 In holiness and righteousness before him, all the days of our life.
76 And thou, child, shalt be called the prophet of the Highest: for thou shalt go before the face of the Lord to prepare his ways;
77 To give knowledge of salvation unto his people by the remission of their sins,
78 Through the tender mercy of our God; whereby the dayspring from on high hath visited us, (Luk 1:67-78 KJV)
KJV Mark 1:1 The beginning of the gospel of Jesus Christ, the Son of God;
2 As it is written in the prophets, Behold, I send my messenger before thy face, which shall prepare thy way before thee.
3 The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
4 John did baptize in the wilderness, and preach
the baptism of repentance for the remission of sins. (Mar 1:1-4 KJV)
Salvation through the remission of sins. Water baptism for the remission of sins.