Calvinism teaches that God foreknows because He decreed that man would act a certain way, and thus man necessarily acts a certain way and God can be certain of that.
To declare God’s glory is to talk about His greatness. God is great, and He is more than worthy of all praise and glory.
There is nothing contradictory nor deficient in understanding the biblical portrait of man’s knowledge being uncertain while God’s is certain
the Calvinist idea is that all actions are predetermined by God either through decrees, compatibilism, or both and this makes everything certain and therefore knowable.
Because Jesus Christ forgives and cleanses us of all our sin when we place our faith in Him and experience salvation, we are tempted to disregard our continued sin and how God might deal with it.