On our own we can’t ever “KNOW”. I am so thankful that Jesus left us a Church to guide us into all truths.
We are but sheep, Jesus tells us this over and over again. Lucky for us we don’t have to run around like lost sheep because He also left us a shepherd.
Stick close to the Sacraments He left us. The Sacraments are the visible signs that will strengthen us and let us know we are doing all that He commanded.
God Bless