How do we know Christ's salvation is effective?

The effectiveness of Christ's salvation can be seen throughout the Scriptures, where it is affirmed that He has saved us and called us with a holy calling, not according to our works but according to His purpose and grace (2 Timothy 1:9). The victory over our spiritual enemies is secured in His death and resurrection, which is prefigured in the triumph of David over Goliath. Christ accomplished our redemption on the cross, declaring that it is finished (John 19:30). This guarantees that all for whom He died will be saved, showing the certainty and effectiveness of His atoning work, as evidenced in passages like Romans 8:30.