I'll start by saying that there are no well respected seminaries that teach that a believer can lose his/her salvation. Before you counter with a list of Bible colleges that do teach it, I would take a look at 1) is it the official position of the college? and 2) what are the credentials of the men who are teaching and administrating that college?

That being the case, I can't say that I believe that there are any "cons" to the position that a believer is eternally secure. The disagreement arises from the lack of a dispensational approach to the scriptures and from a lack of understanding of what is said to Israel as a nation, what is said to the whole church or to individual churches (Revelation 2-3) and what is said to individual believers. To believe that God is unable to uphold a saved person, even in his most backslid condition, is an affront to God and an attack on His character and nature. The old hymn states it very well:

My sin, oh, the bliss of this glorious thought!
My sin, not in part but the whole,
Is nailed to the cross, and I bear it no more,
Praise the Lord, praise the Lord, O my soul!

If Jesus paid for ALL my sin, that includes sin that I have not even considered committing yet and that is still future. If my future sin is paid for, but God charges me with it when I commit it in the future, then He is guilty of violating the law of double jeopardy. Once sin is paid for, I cannot be charged for it again or God is unjust.

For those that say that salvation can be lost if a person "stops believing", there are three problems. First of all, it places merit on the exercise of faith. Secondly, it begs the question of how "weak" does my faith have to become before I have lost salvation? Thirdly, it leaves out the fact that profession of faith does not equate to possession of faith.

Finally, if I were to believe that I could lose my salvation, I would be extremely incapacitated toward any long range planning for my Christian life. I could never say anything more than, "I'm saved today, but I don't know about tomorrow." As to implications on our Christian walk, I think that the idea that a person can lose his salvation leads either to pride or to self-condemnation; pride when the person is doing well, and self-condemnation when he is not doing well or when he has recently failed. That idea also leads to a very critical and judgmental attitude toward others. I think one of the most powerful verses in support of eternal security is Romans 14:4Who are you to judge another's servant? To his own master he stands or falls. Indeed, he will be made to stand, for God is able to make him stand. "Who are you to judge another’s servant? To his own master he stands or falls. Indeed, he will be made to stand, for God is able to make him stand."

This is a very extensive subject, and I'm sure others will add more, but these are just some quick initial thoughts.

Great topic. Many people struggle with thinking they can lose their salvation. I know I did. What changed my thinking? Losing my salvation was a tremendous fear. What changed? How did I become secure in my salvation. I began to study the character and nature of God categorically . This helped me to see I had been attributing the sinful human characteristic of unforgiveness that produces broken relationships to God's relationship with me. His attribute is forgiveness and He does not change.

2 Timothy 1:9who has saved us and called [us] with a holy calling, not according to our works, but according to His own purpose and grace which was given to us in Christ Jesus before time began, who has saved us and called us with a holy calling, not according to our works, but according to His own purpose and grace which was given to us in Christ Jesus before time began.

2 Timothy 2:13If we are faithless, He remains faithful; He cannot deny Himself. If we are faithless, He remains faithful; He cannot deny Himself.

Mal 3:6"For I [am] the LORD, I do not change; Therefore you are not consumed, O sons of Jacob. I am the Lord, I do not change; therefore you are not consumed, oh sons of Jacob.

I have friends that believe you remain secure in your salvation as long as you "abide in Christ" referring to the John 15 verses 1-11.  You could say Amen, but the statement implies that maybe you could choose not to abide once you have.  Pastor Wood dealt with this in Sunday School yesterday with great clarity.  Maybe he can post the tenses of the word "lift up" or "take away" (Greek word Airo)?  Also comparing the words "You" and "anyone" really gave clarity to this passsage as well. 

I had heard the definition of the Greek before but it seemed inconsistant to have discipleship and salvation being referred to in the same passage until Pastor Wood explained the tense of the word "Abide" being a completed action at a point in time.  It is comforting and restful to know that I am in Christ and He WILL bring forth fruit in my life by "lifting" me up so that I don't rot in the muck.