Perhaps the most deadly sin of the unbeliever is that of procrastination. Satisfied with his current life, he neglects his spiritual need. Even if he understands the gospel and realizes his need of salvation, he still puts off a decision.
But it is always dangerous to count too strongly on tomorrow. "Whereas ye know not what shall be on the morrow. For what is your life? It is even a vapour, that appeareth for a little time, and then vanisheth away" (James 4:14). The sin of procrastination may easily become the sin of negligence, then of indifference, and finally, the unforgivable sin of irrevocable rejection and unbelief. "My spirit shall not always strive with man" (Genesis 6:3). This warning was true in the antediluvian world and it is certainly as true today, when we have far more knowledge and evidence of God's truth and His will than people did in the days of Noah.
"To day if ye will hear His voice, Harden not your heart" (Psalm 95:7-8). This warning of the psalmist was considered so important that the writer of Hebrews quoted it three times (Hebrews 3:7-8,15; 4:7). Such an emphasis suggests there is indeed great danger in resisting God's call to salvation. There may be another opportunity, but it is presumptuous and dangerous to impose too long on God's patient mercy.
Today is the day of salvation. The accepted time is now! "Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace? . . . It is a fearful thing to fall into the hands of the living God" (Hebrews 10:29,31). HMM