Examine ourselves, whether we are still in the faith unless we are disqualified because of the temptation.
Jas 1:14-15 But every man is tempted, when he is drawn away by his own lust, and enticed. Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death.
Sin out of ignorance may be forgiven as Paul knowing Jews' religion as the truth persecuted the Church of God but later preached the faith which once he destroyed.
Heb 10:26-27 For if we sin willfully after we have received the knowledge of the truth, there remaineth no more sacrifice for sins, But a certain fearful apprehension of judgment and fiery indignation, which shall devour the adversaries.
Once we receive therefore the salvation offered and we become abusive, careless and neglect His will then it's forfeited.
1 Chro 28:9 And thou, Solomon my son, know thou the God of thy father, and serve him with a perfect heart, and with a willing mind: for the LORD searcheth all hearts and understandeth all the imaginations of the thoughts: if thou shalt seek him, he will be found of thee; but if thou shalt forsake him, he will cast thee off for ever.
Set our hope fully upon the grace stored for us at the coming of Jesus Christ.
1 Pet 1:14-16 As obedient children, not fashioning yourselves according to the former lusts in your ignorance: But as he who hath called you is holy, so be ye holy in all manner of deportment. Because it is written, Be ye holy; for I am holy.
So the next time we read below the first requirement of salvation which is believing in Him, think of the works expected of a believer.
Jn 3:16 For God so loved the world, that he gave his only-begotten Son, that whoever believeth in him, should not perish, but have everlasting life.
Let us look to ourselves then, that we lose not those things which we have acquired that we may receive the full reward so as not to be marked "forfeited".