Eternal Salvation is Forever and Saved by Faith (not Works)
"The test of the Gospel is grace. If the message excludes grace, or mingles law with grace as the means either of justification or sanctification (Gal 2:21; 3:1-3), or denies the fact or guilt of sin, which alone gives grace its occasion and opportunity, it is 'a different' gospel, and the preacher of it is under the anathema of God." (Scofield Study Bible, footnote for Galations 1 8-9)
Dr. J. Vernon McGee has a very good study on Is it Possible for a Saved Person Ever to Be Lost?
The following three books (although out of print now) were written by James White, a Christian Apologist and Director of Alpha and Omega Ministries in Phoenix, Arizona.
- God's Sovereign Grace explains God's sovereignty and Mans inability to come to saving faith by himeslf;
- Justification by Faith, shows how justification does not come from man's works, but faith, which is itself a gift from God; and also,
- Drawn by the Father: A Study of John 6:35-45, which shows how Christ will never lose one of those whom God Himself has given to Him.
Saved by Faith
For scriptures that explain salvation check out Saved by Faith Through Grace
Word of Truth ministries has numerous tapes by Chet McCalley that clearly outline Saved by Faith through Grace not by Works (see the series "Security of the Believer"). They also explain very clearly why Lordship Salvation is not Scriptural, i.e., "making" Christ Lord of your life before you become a believer.