Is the gospel of Jesus Christ something that should be believed to "get in" to the faith and then placed aside?
No, the gospel is central not only to justification (entrance into Christianity) but also for sanctification (continuing to grow in grace, evidencing genuine faith), and glorification (being absorbed into the glory of God in heaven). Here are some helpful resources that exalt the centrality of the gospel of Jesus Christ for an entire life of faith.
The Cross Centered Life
God is the Gospel
Redemption Accomplished and Applied