God is oppossed to the proud and gives grace to the humble.
2 Tim 2:22-3:1
23 But refuse foolish and ignorant speculations, knowing that they produce quarrels. 24 And the Lord's bond-servant must not be quarrelsome, but be kind to all, able to teach, patient when wronged, 25 with gentleness correcting those who are in opposition, if perhaps God may grant them repentance leading to the knowledge of the truth, 26 and they may come to their senses and escape from the snare of the devil, having been held captive by him to do his will. NAS
2 Cor 12:20-21
20 For I am afraid that perhaps when I come I may find you to be not what I wish and may be found by you to be not what you wish; that perhaps there may be strife, jealousy, angry tempers, disputes, slanders, gossip, arrogance, disturbances; 21 I am afraid that when I come again my God may humiliate me before you, and I may mourn over many of those who have sinned in the past and not repented of the impurity, immorality and sensuality which they have practiced. NAS
Romans 4:19-25
19 And without becoming weak in faith he contemplated his own body, now as good as dead since he was about a hundred years old, and the deadness of Sarah's womb; 20 yet, with respect to the promise of God, he did not waver in unbelief, but grew strong in faith, giving glory to God, 21 and being fully assured that what He had promised, He was able also to perform. 22 Therefore also it was reckoned to him as righteousness. 23 Now not for his sake only was it written, that it was reckoned to him, 24 but for our sake also, to whom it will be reckoned, as those who believe in Him who raised Jesus our Lord from the dead, 25 He who was delivered up because of our transgressions, and was raised because of our justification.
NAS
We can be assured of our salvation because God is not a promise breaker.
Paul did not live in fear of loosing his salvation; he worked at being a righteous bond-servant to his Holy Master; works that are ordained of and by God.