The conscience gives ambiguous and self-contradictory guidance. It brings us exactly 0% closer to God. The only way to God is Christ.
John 14:6
Jesus saith unto him,
I am the way, the truth, and the life: no man cometh unto the Father, but by me.
The only good thing the conscience can do is judge you as a sinner so that you would turn to Christ. Apart from that, all the conscience does is encourage you to sow to the flesh: “I can be better, I can earn blessings, I can sin less.”
Galatians 3:3
Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?
Your spiritual life begins with Christ and is sustained by Christ. The flesh doesn’t contribute to it.