Life presents reasons to disobey God.
God places you in situations in life where it is easy to disobey God and do what you think is best for your life. 1 Samuel 13 presents us with a situation where King Saul finds it expedient to disobey the Word of God rather than obey.
Saul is facing imminent danger as a large force of Philistine warriors are ready to attack the Israelites. Moreover, the Philistines are armed with the latest weapons of the Iron Age, while the Isralites are left with only rocks, sticks, and slingshots. On paper, the Philistines have all the advantages: they have superior weapons and superior numbers. This could be a disastrous defeat for Israel.
King Saul was instructed to wait seven days for Samuel the prophet to arrive and offer sacrifices to God before they went to war. But with Saul's men abandoning their posts, with many hiding in caves and tombs, and some just running away to survive, Saul decides to just get on with the sacrifices himself since Samuel has not showed up. In other words, Saul decided to disobey the Word of God because it seemed like the right thing to do to survive against the Philistines army. Just get the sacrifices over with and get ready to fight before the Philistines attack and before Saul loses any more soldiers.
Saul's disobedience seemed reasonable to him - it made sense. Surely God would understand why he needed to disobey in order to survive the war.
But disobeying God is never reasonable. Disobeying God is never expedient. Disobeying God never pays off.
It didn't work for Saul and won't work for you. Instead of lacking faith and acting on impulse, Saul should have remembered God's promises to him (see 1 Samuel 10, 12). Similarly, when life presents opportunities to disobey God's Word you should remember God's promises to you.
What are those promises?
God promises that those who repent and trust in Jesus Christ have their sins forgiven, are adopted into God's family, have Christ's righteousness imputed to them, have the presence of the Holy Spirit with them, have the hope of a physical resurrection, and the promise of eternal life with the Triune God.
Those are God's promises of grace to you based on the redemptive work of Jesus Christ. God doesn't ask you to earn them or work hard to merit his grace. Rather, God promises them to you based on what Jesus Christ has earned for you at the cross. God promises them to you based on what Christ merited for you through his atoning death and triumphant resurrection from the dead.
Life presents opportunities to disobey. Yet, when those opportunities arise God's Word instructs us to reflect not on the difficulty of our circumstances, but on his covenant of grace to you.