Acts 8:36As they went along the road they came to some water; and the eunuch said, “Look! Water! What prevents me from being baptized?”
Baptism is a mark, recognising an act of belief. The Ethiopian eunuch believed Christ was the Rest, the destination, the state, the means, by which a believer becomes a blessing to the world, and could ask for the mark.
Salvation is not "going to heaven". There is very little information in Scripture about the afterlife, and whatever views Israel held was mostly influenced by being exposed, while in exile, to the views of the Babylonians. Even today, there is no halakhic, compulsory, Orthodox, view about the afterlife and Jews are free to believe whatever they want about it.
First century believers were more interested in the promise God made to Abraham, that his children could hope to have a noble vocation, to be blessings to the world, to be a Light to the Nations. So Christians were considered to be saved, if they began the process of drinking from the Rock, growing in faith, and finally entering “Rest”, becoming that blessing, the journey started by being baptised, and completed by obeying God’s voice when He called for a decision.
In other words, what WILL save is obedience, learnt from suffering, experienced when baptised:
1 Peter 4:12Beloved, do not be surprised at the fiery ordeal among you, which comes upon you for your testing, as though some strange thing were happening to you; 13but to the degree that you share the sufferings of Christ, keep on rejoicing, so that also at the revelation of His glory you may rejoice with exultation.
Hebrews 5:8Although He was a Son, He learned obedience from the things which He suffered.
Matthew 4:1Then Jesus was led up by the Spirit into the wilderness to be tempted by the devil. 2And after He had fasted forty days and forty nights, He then became hungry. 3And the tempter came and said to Him, “If You are the Son of God, command that these stones become bread.” 4But He answered and said, “It is written, ‘MAN SHALL NOT LIVE ON BREAD ALONE, BUT ON EVERY WORD THAT PROCEEDS OUT OF THE MOUTH OF GOD.’”
Bible interpretation is difficult, because the information is complex, and polyvalent, containing many different ideas in one passage. It is like looking at a tree. You get information about the trunk, branches, roots as they appear and disappear among the leaves and the undergrowth, like different threads in a tapestry. The tree is not the branch. If you want information about what the tree is, you must first isolate and extract all information about the branch, the trunk, the roots and maybe even the leaves. This happens in the study of the Atonement, which has different interpretations : penal substitution, satisfaction, ransom, moral exemplar, Christus Victor, etc. These are branches, but not the tree. What term explains the Atonement comprehensively?
Another example is blood. Blood carries oxygen to the different parts of the body, so it helps in respiration. It also carries nutrients, so it part of the nutrition system. It sends white blood cells to fight infection, so it immunises. The comprehensive explanation of the function of the blood in our bodies is that it is a carrier, a vector, for all the entities that do respiratory, nourishment, immunisation, etc. duties.
So I have been careful to explain that the object that saves is obedience. In order to deal with the idea that baptism also clears your conscience, I provided an answer in another, older thread. Unfortunately, it is in the Christianity section, so did not appear close to this answer.
In what manner did Christian baptism differ from ritual washing as part of Jewish Teshuva (repentance.)
I repost it here:
Teshuva is performed in a pool, in addition to the ritual cleansing required for the various contaminations listed in Torah: contact with dead bodies, men with emissions of semen, menstruating women, etc. There is no teachings about teshuva in the Tanakh, and its observance would not have been possible in the wilderness. It was formed through tradition, and also became a necessary ritual for conversion to Judaism.
Baptism is NOT cleansing from contaminations either listed above, or more. It is a mark signifying compliance by the candidate, that he has believed that Christ is the Rest promised by God to Abraham, the destination, the shelter, the harbour, the city, the country, where the candidate can stop from his labours, can end his travelling. Prompted by his conscience, with his judgment taking all things into consideration, including God's display of great saving acts, like Abraham's rescue from the kings who kidnapped Sarah, and Israel's rescue by the water flowing from the Rock. Every believer will experience rescue. Now God accepts his clearing his conscience of any guilt that he has not obeyed.
1 Peter 3:21Corresponding to that, baptism now saves you—not the removal of dirt from the flesh, but an appeal to God for a good conscience—through the resurrection of Jesus Christ,
The effect of this baptism is that the believer is immediately inducted into a course of edification, building up of faith. God created calamities, dangerous situations like famines and then rescued. You can see this happened with Abraham, and the children of Israel in the wilderness. Whilst Abraham learnt obedience through suffering, Israel did not. But even Abraham and many other successful heroes of faith did not receive the Rest promised. They were to be fulfilled only together with those who did receive the Rest.
Hebrews 11:13All these died in faith, without receiving the promises, but having seen them and having welcomed them from a distance, and having confessed that they were strangers and exiles on the earth. 14For those who say such things make it clear that they are seeking a country of their own. 15And indeed if they had been thinking of that country from which they went out, they would have had opportunity to return. 16But as it is, they desire a better country, that is, a heavenly one. Therefore God is not ashamed to be called their God; for He has prepared a city for them.
Hebrews 11:39And all these, having gained approval through their faith, did not receive what was promised, 40because God had provided something better for us, so that apart from us they would not be made perfect.
All Scripture from the NASB.