The Greek language tends to be much more precise than English and in many cases ignoring the details of the Greek will lead to misunderstandings. An example which pertains to the doctrine of Eternal Security is Acts 16:31, where Paul and Silas tell the jailer what is necessary to be saved:
Believe on (rely on, trust in) the Lord Jesus Christ and you will be saved.
In the English, the verb tense of "Believe" is rather ambiguous. But the Greek reveals something a little different. In the Greek, the verb here is "pisteuo" and it's in the Aorist tense. The Aorist tense has a specific meaning… it literally refers to an action that happened in the past, but whether the action is ongoing or continuous is not specified. In other words, it might continue and it might not.
The implications of this is profound. If you place your trust in Christ at a point in time, then you are saved whether or not that trust continues!! The Aorist tense here means that you might continue to believe; and you might not. But in either case, you will be saved. There's no room there for doubt.
Just one more to go…