Believe on the Lord Jesus and you will be saved.
This statement in Acts 16:31 uses "believe" in the aorist tense. It's punctiliar action, not linear action. "Will be saved" is indicative; it's a simple statement of what will happen, based upon the action of "believe" in the aorist.
What do you need to believe? On the Lord Jesus. That he died in your place that if you accept the free gift that's being offered, you will be saved.
"Believe" in the present tense is a requirement for obedience, and when used as a participle is synonymous with the noun "faith".
"Believe" is not a difficult concept. But, many people want to make it such.
As to "eternal", Lacy, you are correct that context can determine its meaning. However, if you look at the original language, you don't even need to look at context; it's explicit.
Although in modern English, we use terms such as "the light took forever", properly, "eternal" means "without beginning or ending" or "existing outside of time". The Greek word to which this is closest is "aidios", which is used only twice in the Bible.
"Everlasting", which properly means "without ending", is a Greek phrase εις τοὺς αιωνας των αιώνων or literally “from the ages unto the ages”. It is used in several places in the Bible and is usually translated in the KJV as "forever and ever" or something similar. This expression is found in Gal 1.5, Eph 3.21, Phl 4.20, 1Tm 1.17, 2Tm 4.18, Rev 1.6, Rev 1.18, Rev 4.9, Rev 4.10, Rev 10.6, Rev 11.15, Rev 14.11 (no definite article), Rev 15.7, Rev 19.3, Rev 20.10, Rev 22.5. (Please note that Revelation 14:11 does not contain the definite article, so it is simply “ages of ages”, which simply means a long time.)
However, the Greek word "aionios", means literally “age-lasting”. It is often translated variously as eternal, everlasting, or whatever suited the fancy of the translator at the time. It is from the noun "aion". "Aionios", by definition, has to do with a specific period of time; the Kingdom age.
To take a quote from
Dualism of Eternal Life by S. S. Craig:
The Latin Vulgate translated the Greek adjective aijw>niov to the Latin aeternus in which we get the English word eternal and eternity. The KJV translators instead of going back to the original Greek and translating the Greek adjective aijwniov, went to the Latin Vulgate and translated the Latin aeternus. This is why the word eternal has been misunderstood by the English reader. If they would have gone to the Greek they for sure would have translated it as many translators such as Rotherham and Young, namely, age lasting or life for the age (eijs ton aijw>niov).
It is equally a fact that the theology of the West was not that of the Greek Church but that of Roman Catholicism. It was Latin theology. And just as it is beyond doubt that the revisers, translators, and lexicographers, were chiefly influenced by the Latin language and Latin translations. It is admitted that the theology of Calvin was derived from Saint Augustine, modernized and extended.
“It was absolutely essential to Augustinian theology with its blightening emphasis on the doctrine of predestinarianism to mistranslate the Greek adjective aijwniov, and put on it a meaning which the Greek will not for a moment allow in its respective applications to salvation and judgment.
And that was essential to Augustinian theology was equally essential to Latin Christianity from the days of Augustine to those of Calvin and Luther. And the same exists in the Reformed Theology from then till the present.
To say nothing of other words, the Calvinist simply cannot, dare not, face an honest and truthful interpretation of the two frequently occurring words with which we are now dealing with, namely “eternal life”.
If you would like to download the verse lists and parsed verses for each of these words/expressions, right click and save the following links:
Ages Unto Ages
Age-Lasting
Eternal
Ages