Second Answer from Affirmative

TurretinFan asks,

Given your comment, "God desires that none of His apostatize," (yet seemingly God might not prevent apostasy) is God able to keep people from falling away into apostasy or does something (man's free will?) stop God from keeping them from falling?


Answer:

God can do whatever He pleases within the range of His holy nature, nobody prevents Him. If God didn't care if we apostatized, He wouldn't give us sustaining grace enough to endure. The fact that men can still fall away despite His provision is easily reconciled by the fact that He doesn't choose to apply His grace irresistibly. I'd pointed out this concept in 1 Corinthians 10:13, which states that God won't allow us to be tempted beyond what we can endure. 'Can' does not amount to 'will;' believers sometimes do fall, but due to our own failures, not want of God's help.

His provision is evidenced in several passages often mistaken for support of eternal security. John 10:27-29 and Romans 8:35-39 for instance express that no one will ever tear us away from God (as countless martyrs for Christ have by their deaths triumphantly testified), but nowhere does scripture indicate that it's impossible to willfully walk away from Him, since apostates themselves don't separate/pluck themselves from God -scripture clarifies that God the Father Himself severs those who don't remain in Christ (John 15:1-6). Hence, arguments such as the sealing with the Holy Spirit guaranteeing eternal security miss the mark as to how one can be lost: Since the sovereign God has both power and prerogative to cast out those who don't abide, His own seal is no bar to Him doing so. Having the Spirit is both a gift and responsibility, for those in which the Spirit dwells are the temple of God,

...If anyone defiles the temple of God, God will destroy him. (1 Corinthians 3:17b)

According to the riches of His grace, God preserves us, sustains us, and works in us to will and do His good pleasure, yet the apostles still plead with us, "not to receive the grace of God in vain" (2 Corinthians 6:1b). God is able to keep us from stumbling and to make the weak in faith to stand (Romans 14:4), yet we are still told,

Therefore let him who thinks he stands take heed lest he fall. (1 Corinthians 10:12)

It's only by God's grace that the heart can be established in persevering, but the scriptures never portray the operation of grace as something unconditional or irresistible. Grace to endure is never merited, nor is it inescapably instilled, but when enduring temptation it's written,

Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need. (Hebrews 4:16)

So God is able to keep us from falling, but doesn't choose to do so apart from our willing cooperation (we being freed by His grace to serve Him -Hebrews 12:28), and thus He warns us against the real dangers of apostasy and exhorts us to seek Him,

...be all the more eager to make your calling and election sure. For if you do these things, you will never fall. (2 Peter 1:10b)