Welcome to the course!
You have probably heard that once a believer is saved, they are always saved. True - once a person believes in Jesus Christ, few things happen. God justifies that person. The believer is declared righteous, that person is adopted into God's family, and there is assurance.
But once a person is accepted and brought into God's family, that does not give us a right to live their lives as we wish.
Christian living matters. And it is important to God. Sometimes, the verse the apostle John says scares me a bit: "Whoever says “I know him” but does not keep his commandments is a liar, and the truth is not in him." 1 John 2:4. Christian life means keeping up the commandments of the Lord. Christian life means to "know Him," which is also eternal life, according to John 17:3. How can one know Him? By reading the Scripture that God has given us. The Psalmist says in Psalm 119:8, "How can a young man keep his way pure? By guarding it according to your word."
The Christian life is more than reading the Scripture; it is more than attending Church services. It has to do with a personal relationship with the Lord and walking in His ways.