Myself and others have concluded that to RECONCILE the eternal security NT verses with those verses that are opposed to them ... we need to understand what is really meant by that one word "believe"! To reconcile all of the verses, we see this in the NT:
True saving FAITH = deep heart-felt belief + enduring faith + strong trust + obedience or ... True saving BELIEF = deep heart-felt and enduring faith + strong trust + obedience
There is NO one word in any language which encompasses all of these concepts,
so translators just use the word "believe". But, we know that far more than intellectual belief is required to be saved.
Not all translators the content must follow the thoughts and the structure of the sentence since the word is
archaic think or believe;
2 Thessalonians 2:13 At all times we are obligated to thank God for you, brothers who are loved by the Lord, because God chose you to be the first fruits for salvation through sanctification by the Spirit and through
faith in the truth.
G4100 πιστεύω pisteuō πιστευει believe, trow, OE truuwian, trēowian 'to trust';
archaic think or believe; credit; (v. t.) To confide in the truth of; to give credence to; to put trust in; to believe.
From G4102 πιστιν, πιστεως πίστη faith, belief, trust, conviction
G 4103 πιστος faithful, trusty, credible, pledge, security, warrant
G3982 πεισαν πείθω persuaded, convince, determine, obey, prevail on, talk over, mislead, tempt, trust, rely on, believe of, confidence