Hope,
bmerr here. If Acts 16:31 were the only verse that dealt with salvation, then you would be correct. However, the Bible has much more to say about salvation than, "Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house".
Just the immediate context of the verse shows that the Phillipian jailor (PJ) may have been hearing the name of Jesus for the first time when Paul and Silas told him the above words.
The very next verse has Paul and Silas speaking unto PJ the "...word of the Lord, and to all that were in his house" At this point, and not before, we can be sure that PJ had heard the word of God, whereby cometh faith (Rom 10:17).
We then see his repentance demonstrated as he washes their stripes, and we see that he and his household submit to baptism that same hour of the night.
Following all of these things, we read that PJ "...rejoiced, believing in God with all his house" (16:34). His faith, repentance, and baptism are all summed up with the phrase, "believing in God", which is equivalent to believing on the Lord Jesus Christ.
Concerning the possibility of forfieting one's common salvation, there are many warnings to Christians about not giving up, keeping the faith, not turning back to the world. Rom 6:16 is one of them, which reads,
"Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?"
I don't think physical death is what Paul is speaking of here. Even the righteous die physically, and nothing, save the 2nd coming, will keep that from happening. The only other option is spiritual death.
One becomes a servant of Christ by obeying Christ. If one stops obeying Christ, and returns to obeying his own sinful lusts, then he becomes the servant of sin.
In Luke 12:42-48, Four types of people are described:
- the faithful servant (42-44) - Called "that servant". Did the will of his Lord faithfully. He is the only one rewarded by the master.
- the wicked servant (45-46) - Called "that servant". Forsook his Lord, and returned to the ways of the world, and is given the most severe punishment. Cut asunder and given his portion with the unbelievers.
- the lazy servant (47) - Called "that servant". Knew his Lord's will, but didn't do it. His punishment is less severe than the wicked, but is not rewarded. Beaten with many stripes.
- the unbeliever (48) - Is not called "that servant", but is referred to merely as "him". Knew not the Lord's will. Did things worthy of stripes, but is only "beaten with few stripes".
Only one of those listed as "servant" is rewarded. At least one of those listed as "servant" is given his portion with the unbelievers, which we all understand is hell. Both the wicked servant and the lazy servant recieve more severe punishment than the unbeliever, and I don't think any of us would say that unbelievers go to heaven.
I don't know how any other conclusion can be reached than that the wicked and the lazy servants of the lord of the parable ended up in worse shape than the unbeliever. If that isn't a loss of one's salvation, I don't know what it is.
In Christ,
bmerr