@{
ViewData["Title"] = "My apps login title";
// Making this nullable makes it so I don't
// have to pass a false boolean when I'm not postbacking
bool? failedLogin = (bool?)ViewData["failedLogin"];
}
<h2>My Application's name goes here</h2>
<form method="post">
    <div class="form-group">
        <div class="form-group">
            <label for="email">Username:</label>
            <input type="text" class="form-control" id="username" name="username">
        </div>
        <div class="form-group">
            <label for="pwd">Password:</label>
            <input type="password" class="form-control" id="password" name="password">
        </div>
        <div class="checkbox">
            <label><input type="checkbox"> Remember me</label>
        </div>
        @if (failedLogin == true)
        {
            <div class="text-danger form-group">
                Invalid Username and/or password
            </div>
        }
        <button type="submit" class="btn btn-default">Submit</button>
</form>

[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Index(string username, string password)
{
    // I don't like seeing (using() {} everywhere in my code. I like to hide the ugliness)
    var matchedUser = ProgramWideFunctions.getUserByUserNameAndPassword(username, password);
    if (matchedUser != null)
    {
        HttpContext.Session.SetString("username", matchedUser.username);
        return RedirectToAction("ControlCentre");
    }
    else
    {
        ViewData["failedLogin"] = true;
        return View();
    }
}

public static KAPUsers getUserByUserName(string username)
    {
        using (var db = new AlertsDbContext())
        {
            return db.KAPUsers.Where(b => b.username == username).FirstOrDefault();
        }

    }

    public static KAPUsers getUserByUserNameAndPassword(string username, string password)
    {
        using (var db = new AlertsDbContext())
        {
            return db.KAPUsers.Where(b => b.username == username && b.password == password).FirstOrDefault();
        }

    }