Can faith alone save anyone?
Yes, it is by faith alone as it's afree gift from God. Read Hebrews Chapter 11 plus these scriptures I listed below. There is no amount of actual water that can save anyone, but yet it should not be forbidden that anyone should not be baptized in water.
John 3:16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. 17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
Romans 10:9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. 10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. 11 For the scripture saith, Whosoever believeth on him shall not be ashamed.
Ephesians 2:8 For by grace are ye saved through faith; and that not of yourselves:
it is the gift of God:
Matthew 3:2 John's baptism was for repentance as he said, "Repent ye: for the kingdom of heaven is at hand." The kingdom of heaven was only coming near as John was calling those to prepare themselves through repentance to be prepared for the kingdom of heaven. The Jews already had faith in God, but yet could not believe in Messiah come as Jesus had not come to begin His ministry yet. That happened when
John 3:5 never mentions the word baptize, but says only by being born of water and spirit, which means water as living water (word of God) that no one can enter into the kingdom of God unless they are Spiritually renewed (born again) by the hearing of the word, which is Christ Jesus and by the Holy Spirit that came on them in the OT and indwells us in the NT. Many do read into the passage a preconceived idea or theology, but baptism is never mentioned in this verse. Word is living water as described in John 4:10; 7:38; 1John 5:6; Jeremiah 2:13; Isaiah 55:1-3 to name a few.
If salvation came by actual immersion in water Jesus clearly could have simply stated, "Truly, truly, I say to you, unless one is baptized by being immersed in water and born of the Spirit, he cannot enter into the kingdom of God.” Further, if Jesus had made such a statement, He would have contradicted numerous other Bible passages that make it clear that salvation is by faith (John 3:16; John 3:36; Ephesians 2:8-9; Titus 3:5).
Baptism is not mentioned in John chapter three so why do so many believe we are to be dunked in dirty river water as the water can not bring about Gods salvation, but only by faith do we believe as it comes by Gods grace, Ephesians 2:1-10, as we hear the gospel (word/living water) preached to us.
John's baptism was literal, but yet symbolic for cleansing after one repented of their sin. Notice in Mark 1:8 I have baptized you with (actual) water, but he (Jesus) will baptize you with the Holy Spirit. (Not water, but baptize you with the Holy Spirit after you have repented and made clean again through the washing of the word as you become a new creation in Christ.
Jesus never baptized anyone in literal water that we know of and also instructed the Disciples to wait upon the indwelling of the Holy Spirit, Acts chapter 1, and then commissioned them to go out preaching the Gospel (word/living water) and to baptize in the name of the Father, Son and Holy Spirit, Matthew 28:16-20.