The tense shows the type of kind of action that is being communicated. In the Greek language, verb tenses differ from English verb tenses in that the kind of action portrayed is the most important part of what is being communicated and time is a relatively minor consideration.
Action as Continuous
Present tense: continuous action. This is primarily progressive or linear; it shows action that is continuing.
Tim is studying the Bible.
"As the branch cannot bear fruit of itself unless it abides in the vine, so neither can you unless you abide in Me" (John 14:4b).
"If anyone does not abide in Me" (John 15:6).
Imperfect tense: continuous action, usually in the past.
Tim was studying the Bible.
"If you were of the world, the world would love its own" - literally, "would have been loving" its own (John 15:19a).
Action as Completed
Perfect tense: punctiliar action in the past with the results continuing into the present. (Punctiliar action is action that happens at a specific point in time.)
Tim is being transformed by having studied the Bible.
"You are already clean because of the word which I have spoken to you" (John 15:3).
"Just As I have kept my Father's commandments and abide in His love" (John 15:10b).
Pluperfect tense: punctiliar action in the past with the results continuing in the past.
Tim was transformed because he had studied the Bible.
"For the Jews had already agreed" (John 9:22).
Action as Occurring
Aorist tense: punctiliar action. The aorist tense states that an action occurs without regards to its duration; that is, it denotes the fact of an action without any reference to the length of that action. The aorist tense is like a snapshot that shows (expresses) that an action occurs, while the present tense action is like a moving picture, continuing on.
Tim studied the Bible.
"Abide in Me, and I in you" (John 15:4a).
Future tense: indefinite action to occur in the future. Indicates continuing or punctiliar action in the future.
Tim will be studying his Bible.
"It will be done for you" (John 15:7).
"So prove to be My disciples" (John 15:8).