How can Jesus's actions provide assurance of our salvation?

The sign of Jonah, as discussed by Jesus in Mark 8:12, serves as a profound testament to His divinity and the completion of His work in redeeming sinners. By stating that 'as Jonah was three days in the belly of a great fish, so shall the Son of Man be three days and three nights in the heart of the earth,' Jesus points to His sacrificial death and subsequent resurrection, validating that He has dealt with sin's penalty. According to Romans 1:4, His resurrection is not only the confirmation of His identity as the Son of God but also provides believers with assurance that their debt of sin has been fully paid. This assurance is foundational to Christian hope, where faith rests not on feelings but on the objective truth of Christ's sacrifice and triumph over the grave.