Acts 16:31 - (AMP) - And they answered, “Believe in the Lord Jesus [as your personal Savior and entrust yourself to Him] and you will be saved, you and your household [if they also believe].” Paul did not say believe and get water baptized and you will be saved. Water baptism FOLLOWS believe/saved (Acts 10:43-47; 11:17; 15:8,9).
Because of your church of Christ indoctrination, you are confusing the picture (water baptism) with the reality (Spirit baptism). As Greek scholar AT Robertson said - "a symbol is not the reality, but the picture of the reality." -http://www.biblestudytools.com/commentaries/robertsons-word-pictures/romans/romans-6-4.html
1 Corinthians 12:13 - For by one Spirit we were all baptized into one body—whether Jews or Greeks, whether slaves or free—and have all been made to drink into one Spirit.
Getting water baptized is not how we obey the gospel. We obey the gospel by choosing to believe the gospel. Romans 10:16 - But they have not all obeyed the gospel. For Isaiah says, "Lord, who has believed our report?"
What did Jesus say in John 3:15,16,18; 6:40,47; 11:25,26. BELIEVE. What did Peter say in Acts 10:43? BELIEVE. What did Paul say in Romans 1:16; 4:5; 10:4 etc..? BELIEVE. A false religion is one that perverts the gospel of Christ by "adding works" to it (including water baptism).
Those of the one real Faith are those who have placed their Faith (belief, trust, reliance) in Christ alone for salvation (and not in water and works). There is only one Baptism that places us into the body of Christ and that is Spirit Baptism (1 Corinthians 12:13), not water baptism.
Peter tells us that baptism now saves you, yet when Peter uses this phrase he continues in the same sentence to explain exactly what he means by it. He says that baptism now saves you-not the removal of dirt from the flesh (that is, not as an outward, physical act which washes dirt from the body--that is not what saves you), "but an appeal to God for a good conscience, through the resurrection of Jesus Christ" (that is, as an inward, spiritual transaction between God and the individual, a transaction that is symbolized by the outward ceremony of water baptism). Just as the eight people in the ark were "saved THROUGH water" as they were IN THE ARK. They were not literally saved "by" the water. Hebrews 11:7 is clear on this point (..built an ARK for the SAVING of his household). *NOTE: The context reveals that ONLY the righteous (Noah and his family) were DRY and therefore SAFE. In contrast, ONLY THE WICKED IN NOAH'S DAY CAME IN CONTACT WITH THE WATER AND THEY ALL PERISHED.
Paul clearly teaches that what is signified in baptism (buried and raised with Christ) actually occurs "through faith." Christians are "buried with Him in baptism, in which you also were raised with Him through faith in the working of God, who raised Him from the dead" (Colossians 2:12). Justification on account of union in Christ's death, burial and resurrection is brought about “through faith” - and is properly symbolized by dipping the new believer in and out of the water.
Romans 2:29 - but he is a Jew who is one inwardly; and circumcision is that of the heart, in the Spirit, not in the letter; whose praise is not from men but from God.
Believing saved Paul, just as it saved the jailor as well in Acts 16:31. The first question that must be answered is "when was Paul saved?" Paul tells that he did not receive or hear the Gospel from Ananias, but rather he heard it directly from Christ. Galatians 1:11-12 says, "For I would have you know, brethren, that the gospel which was preached by me is not according to man. For I neither received it from man, nor was I taught it, but I received it through a revelation of Jesus Christ."
Paul had repented (Acts 9:6). "Lord, what will you have me to do?" Repentance means a "change of mind," and is wrought by the grace of God. Paul once persecuted the Lord (Acts 9:5), but is now ready to serve Him demonstrating the fruit of repentance (Matthew 3:8; Acts 26:20). Paul had believed. He had Christ as his Lord (Acts 9:6). The Bible tells us that "no man can say that Jesus is Lord except "by" the Holy Spirit (1 Corinthians 12:3). Paul had, by the work of the Holy Spirit, submitted to Christ as Lord.
Paul prayed (Acts 9:11). "Behold, he is praying," the Lord said to Ananias. This indicates that Paul's praying was pleasing to God. Campbellites teach that God does not hear an unsaved man's prayer, quoting in this regard John 9:31 - "We know that God does not listen to sinners. He listens to the godly man who does his will." Well, Paul was a worshipper of God, calling Christ "Lord" and ready to do His will. All of these things characterized Paul before he was baptized. So, Paul heard and believed in Christ on the road to Damascus. Paul had already believed in Christ when Ananias came to pray for him to receive his sight (Acts 9:17).
It also should be noted that Paul at the time when Ananias prayed for him to receive his sight, he was filled with the Holy Spirit (Acts 9:17)--this was before he was baptized (Acts 9:18). Acts 9 does not specifically tell us when Saul was filled with the Spirit, but verse 17 connects his being filled with the Spirit with the receiving of his sight. *We know that he received his sight prior to his water baptism.
It's also interesting that when Paul recounted this event again later in Acts (Acts 26:12-18), he did not mention Ananias or what Ananias said to him at all. Verse 18 again would confirm the idea that Paul received Christ as Savior on the road to Damascus since here Christ is telling Paul he will be a messenger for Him concerning forgiveness of sins for Gentiles as they have faith in Him. It would seem unlikely that Christ would commission Paul if Paul had not yet believed in Him and was not saved.
This "washing away of sin" in water baptism was only "formal" or symbolic. As Greek scholar AT Robertson points out - baptism here pictures the washing away of sins by the blood of Christ. Water baptism does not wash the soul. This occurred earlier when Paul came to faith in Christ. Jamison, Fausset, and Brown Commentary makes not of the importance of the Greek in Ananias' statement. When Ananias tells Paul to "arise, be baptized, wash away your sins, calling on the name of the Lord," the tense of the last command is literally "having called" (aorist middle participle). "Calling on [epikalesamenos] --- 'having (that is, after having) called on,' referring the confession of Christ which preceded baptism." [Jamison, Fausset, and Brown Commentary, vol. 3 pg. 160]. Kenneth Wuest picks up on this Greek nuance and translates the verse as follows: "And now, why are you delaying? Having arisen, be baptized and wash away your sins, having previously called upon His Name." (Acts 22:16, Wuest's Expanded NT).
*No Scripture is to be interpretated in isololation from the totality of Scripture. Practically speaking, a singular and obscure verse is to be subservient to to multiple and clear verses, and not vice versa.