Christians learn to set their priorities in life in light of the Gospel. 1 Corinthians 2. All acceptable obedience and good works are motivated by the absolute certainty of salvation and final glory, of our being fully entitled to the whole inheritance of eternal life, of our being completely qualified and fit for Heaven, all based on the righteousness of Christ. Without the Gospel, all attempts at obedience and works are no more than dead works, fruit unto death. All Godly assurance is assurance and peace within based on the righteousness of Christ Heb.
Any assurance based on anything else is presumption.
All true worship, acceptable to God, is recognizing, attributing unto Him, all His attributes, His glory, that identifies Him and distinguishes Him from idols. Without the Gospel, all worship is no more than idolatry. The Gospel identifies and distinguishes the true Christ from all counterfeits Phil. Prayer is coming to this God based on the merits of Christ. Without the Gospel, the Scriptures are veiled and locked as far as any real, saving understanding is concerned.